CLEANING OF EQUIPMENT FOR OXYGEN SERVICE - AIGA

CLEANING OF EQUIPMENT
FOR OXYGEN SERVICE
AIGA 012/04
Asia Industrial Gases Association
298 Tiong Bahru Road, #20-01 Central Plaza, Singapore 168730
Tel : +65 62760160 Fax : +65 62749379
Internet : http://www.asiaiga.org

KEYWORDS
• CLEANING
• COMPRESSOR
• ENVIRONMENT
• MEDICAL
• OXYGEN
• PIPING SYSTEM
• PREVENTION
AIGA 012/04
CLEANING OF EQUIPMENT
FOR OXYGEN SERVICE
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© AIGA 2004 - AIGA grants permission to reproduce this publication provided the Association is acknowledged as the source
ASIA INDUSTRIAL GASES ASSOCIATION
298 Tiong Bahru Road #20-01 Central Plaza Singapore 168730
Tel: +65 62760160 Fax: +65 62749379
Internet: http://www.asiaiga.org

Acknowledgement
AIGA 012/04
This document is adopted from the European Industrial Gases Association document IGC 33/97/E
‘Cleaning of equipment for oxygen service’ and acknowledgement and thanks are hereby given to EIGA
for permission granted for the use of their document

AIGA 012/04
Table of Contents
1 Introduction ......................................................................................................................................1
2 Scope and purpose..........................................................................................................................1
3 International Agreements/Regulations.............................................................................................1
3.1.1 Ozone Depleting Substances............................................................................................1
3.1.2 Volatile Organic Compounds.............................................................................................2
4 Cleaning methods ............................................................................................................................2
4.1 Procedure and Agent Qualification...........................................................................................2
4.1.1 General..............................................................................................................................2
4.1.2 Selection Criteria ...............................................................................................................3
4.1.3 Additional Technical Criteria..............................................................................................3
4.1.4 Health, Safety and Environmental Aspects.......................................................................4
4.1.5 Costs .................................................................................................................................5
4.2 Typical Methods........................................................................................................................5
4.2.1 Mechanical Cleaning .........................................................................................................5
4.2.2 Chemical Cleaning ............................................................................................................6
4.2.3 Solvent Cleaning ...............................................................................................................8
4.2.4 Detergent Cleaning .........................................................................................................11
4.2.5 High Pressure Hot Water (Steam) Cleaning ...................................................................12
4.2.6 Emulsion Cleaning ..........................................................................................................12
4.2.7 Rinsing.............................................................................................................................14
4.2.8 Drying ..............................................................................................................................14
4.2.9 Removal of Cleaning Agent.............................................................................................15
5 Cleaning materials .........................................................................................................................15
5.1 Mechanical Cleaning Materials...............................................................................................15
5.1.1 Blast Cleaning .................................................................................................................15
5.1.2 Wire Brushes...................................................................................................................16
5.2 Chemical Materials .................................................................................................................16
5.2.1 Alkaline Chemicals ..........................................................................................................16
5.2.2 Acid Chemicals................................................................................................................16
5.2.3 Solvents...........................................................................................................................17
5.2.4 Water Based Detergents .................................................................................................18
5.2.5 Emulsion Cleaners ..........................................................................................................18
5.3 Cleaning Cloths ......................................................................................................................19
5.4 Desiccating Materials .............................................................................................................19
5.5 Drying/Purging Gas ................................................................................................................19
Table 1: Industrial solvents 1 ..................................................................................................................20
Table 2: Alkaline chemical cleaning materials (Also applicable to Alkaline Detergents)......................21
Table 3: Acid chemical cleaning materials............................................................................................22
Table 4: Common components in alkaline detergents and their main function ....................................23
6 Inspection methods and acceptance criteria .................................................................................24
6.1 Introduction .............................................................................................................................24
6.2 Inspection Methods.................................................................................................................24
6.2.1 Direct Visual Inspection with White Light ........................................................................24
6.2.2 Direct Visual Inspection with UN. Light (Black Light) ......................................................25
6.2.3 Wipe Test ........................................................................................................................25
6.2.4 Solvent Extraction ...........................................................................................................25
6.2.5 Water Break Test.............................................................................................................26
6.2.6 Spectrometric, Chromatographic and other Special Methods ........................................26
6.3 Detection Limits ......................................................................................................................27

AIGA 012/04
6.4 Acceptance Criteria ................................................................................................................27
6.4.1 Odour Test.......................................................................................................................28
6.5 Inspection records ..................................................................................................................28
7 Labelling for oxygen service ..........................................................................................................28
8 Conservation of cleanliness...........................................................................................................28
8.1 Protection Methods.................................................................................................................29
8.1.1 Small Equipment .............................................................................................................29
8.1.2 Large Equipment .............................................................................................................29
8.2 Pressure Testing.....................................................................................................................29
8.3 Notes ......................................................................................................................................29
9 Design and manufacturing considerations for cleanliness ............................................................30
9.1 Quality Assurance for Cleanliness when Buying Equipment or Components........................30
Appendix A: Effect of CFC and VOC on the environment ....................................................................31
Appendix B: Cleaning equipment working with aqueous agents and solvents.....................................32
1 Considerations in the Equipment Selection Process.....................................................................32
Appendix C: Cleaning of carbon steel pipeline .....................................................................................43
Appendix D: Detergent cleaning of pipes with high pressure cleaning equipment...............................46
Appendix E: Cleaning of a tubular heat exchanger in an ultrasonic bath using an aqueous cleaning
agent .....................................................................................................................................................49
Appendix F: Cleaning of parts in an ultrasonic bath using an aqueous cleaning agent .......................50
Appendix G: Cleaning of a vessel with aqueous agent and solvent.....................................................51
Appendix H: Cleaning of a vessel with aqueous agent.........................................................................53
Appendix I: Cleaning of a transportable vacuum insulated vessel .......................................................54
Appendix J: Remedial cleaning on a construction site .........................................................................55

1 Introduction
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Oxygen is not flammable in itself but supports combustion. Oxygen can react with most materials.
The higher the oxygen content and/or pressure in a system:
- the more vigorous the combustion up to explosive levels
- the lower the ignition temperature, up to ignition of materials, that normally do not bum in
atmospheric air
- the higher the flame temperature and combustion velocity.
Care must be taken in the selection of equipment and materials, which need to be oxygen compatible
and free from contaminants. The main contaminants to be avoided and/or eliminated are hydrocarbon
oils and greases, which are easily combustible and particulate matter, which can easy ignite or cause
ignition.
Recognition of oxygen's reactivity led to stringent requirements regarding cleanliness of equipment in
oxygen service.
The first edition of this document issued 1986 recommended procedures and agents to clean and
maintain the cleanliness of surfaces in contact with oxygen, inspection methods and acceptance
criteria as well as practical examples.
Cleaning with solvents (as a main procedure at that time in the oxygen industry) was recommended in
most examples.
The increasingly stringent environment regulations of the last years, regulations including the phasing
out of most chlorofluorocarbons (CFC), restrictions in the use and the banning of some volatile
organic compounds (VOC) led to the necessity to develop alternatives.
This document has been updated to take into account the evolution of the regulations on
environment.
2 Scope and purpose
This document deals with the cleaning of equipment or parts to be used in contact with gaseous or
liquid oxygen and nitrous oxide or oxidizing gases/mixtures with an oxygen index > 25% (see prEN
720-2 or ISO 10156).
Particularly, this document describes cleaning methods, lists cleaning agents, and presents inspection
methods and ways for conservation of cleanliness.
3 International Agreements/Regulations
This section gives an overview of the evolution and current status of the agreements/regulations
phasing out or restricting the use of certain substances for environmental reasons.
3.1.1 Ozone Depleting Substances
Recognition of the contribution of CFCs to the depletion of the ozone layer has prompted a phasing
out of these chemicals.
Since the end of the 70's some countries tried to reduce the emission of CFC by issuing laws, and
after 1980 it was tried by conferences to come to international agreements.
The Vienna Agreement from 1985 was the result of a conference, but no specific measures were
agreed then in the 1987 Montreal Protocol the involved countries agreed on concrete targets in the
reduction of some substances. At the meetings in London 1990 and Copenhagen 1992 the phase-out
dates were advanced and new substances added.
A summary of the European Union legislation on CFCs is as follows

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The phase-out schedule, use, trade, and emission control and reporting provisions for ozone
depleting substances is given in EU Regulation No. 2000/2037 replacing EC No 3093/94on
substances that deplete the ozone layer. . Use of CFC and HCFC solvents is prohibited in noncontained
solvent uses including open-top systems without refrigerated zone. More detailed
information can be found in EIGA Environmental Newsletter No.5.
3.1.2 Volatile Organic Compounds
VOCs are a major source of 'photochemical smog' and ground level ozone that have harmful effects
on human health and the environment.
The main EU legislation covering the use of these substances is EU Directive 1999/13 on the
limitation of emissions of volatile organic compounds due to the use of organic solvents in certain
processes and industrial installations. One of the processes mentioned is surface cleaning.
Installations using solvents above the thresholds specified in the Directive must
• Comply with emissions limit values or solvent reduction plan
• Have a solvent management plan
• Have a permit for their activities
More stringent control measures are required for the most hazardous solvents (with Risk Phrases
R45, 46,49,60,61, i.e. carcinogenic, mutagenic, toxic to reproduction).
The Solvent Management Plan should assist the operator:
- to minimize emissions into the environment
- to verify the limit values of emissions
- to identify solvents which should, be substituted.
Information on the effects of CFC and VOC on the environment and reasons for their banning are
given in Annex 1.
4 Cleaning methods
4.1 Procedure and Agent Qualification
4.1.1 General
This section provides information to be considered when selecting a cleaning procedure/agent for an
oxygen system.
Selection of the appropriate method of cleaning shall be determined by the final level of cleanliness
required as set out in section 4.
There are a number of factors to be considered in choosing the most appropriate cleaning process.
- Technical aspects (process suitability/cleaning effect)
- Environmental and safety aspects
- Economical aspects (costs involved)
The selection criteria can be described as defining the characteristics required in the current situation.
Each solution represents a compromise with advantages and disadvantages.
Before a decision is made about which cleaning method has to be used, the need for cleaning must
be considered and established. It might be possible to reduce cleaning operations by making changes
in the production process.

4.1.2 Selection Criteria
The procedure/cleaning agent should ideally meet the following criteria:
Technical:
- good degreasing properties
- easily removable
- non corrosive
- compatible with commonly used metallic and non-metallic materials
- cleaning agent and its residue to be compatible with oxygen
- non flammable or low flammability
Environmental / Safety :
- non toxic
- non ozone depleting
- environmentally safe
- disposable
Economical:
- inexpensive and readily available on the market
- alternative suppliers
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The American Society for Testing Materials (ASTM) has published for this purpose a guideline G 127,
"Standard Guide for the Selection of Cleaning Agents for Oxygen Systems"
4.1.3 Additional Technical Criteria
Other technical aspects to be considered are:
Size of parts:
- small parts (e.g. up to 500 mm)
- big parts as compressor casings, heat exchangers, vaporisers
Form of parts:
- simple
- complicated/dead ends, crevices
- elongated (pipes)
Surface to be cleaned:
- inner
- outer
- roughness
Location where cleaning is carried out:
- in the workshop
- on the installation site
Period when cleaning is carried out:
- during manufacture,
- commissioning,
- maintenance
State of the equipment to be cleaned:
- assembled
- disassembled
Cleaning frequency:
- continuously

- frequently
- occasionally
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4.1.3.1 Methods to Compare the Efficiency of Cleaning Agents
It is necessary to have standard methods in order to compare the ability of cleaning
procedures/agents to remove oil and grease contaminants from metals.
In principle this can be carried out by contaminating test coupons, cleaning them and evaluating the
cleaning effect by an adequate inspection method.
ASTM has also developed two standards which may be used for these purposes:
- ASTM G 121 "Standard practice for preparation of contaminated test coupons for the evaluation
of cleaning agents".
- ASTM G 122 "Standard test method for evaluating the effectiveness of cleaning agents".
4.1.4 Health, Safety and Environmental Aspects
The ideal agent is non-toxic or at least has a low toxicity. The main factors to take into consideration
are:
- Inhalation effects
- Skin effects
- Eye effects
There are four main issues concerning the environment:
- Emission to water
- Waste disposal
- Emission to air
- Energy.
Energy and emission to water are the main questions for consideration for aqueous cleaning, whilst
emission to the atmosphere is of greater relevance for solvent cleaning.
For environmental aspects see also IGC Technical Note 515/95 "Guidelines for Environmental
Management"
4.1.4.1 Emission to Water
Whichever process is used, contamination of water arises from improper waste disposal, inadequate
effluent water treatment or in the case of solvents, accidental spillage caused by improper handling or
storage.
4.1.4.2 Waste Disposal
Degreasing with solvents gives rise to a residue containing oils, fats and greases. The solvent content
can easily be reduced by distillation either in house or by a licensed recycler, thus recovering useful
quantities of solvent. The residue emerges as a highly concentrated final waste.
This should be disposed of by a licensed contractor and procedures should meet local regulations.
Support and guidance are also available from the solvent suppliers.
Cleaning in an aqueous system generates two types of effluent:
- The spent cleaning bath contains chemical products necessary for the cleaning process and is
also contaminated with oils and greases. This residue must be treated in a wastewater treatment
plant which also generates a sludge requiring further processing before disposal.
- The rinsing effluent is less contaminated, although still containing dissolved salts. Some effluent
may be recycled to an earlier cleaning stage. Any final effluent will require treatment before
discharge.
The regulations for the treatment of spent aqueous cleaning effluent vary considerably from one
locality to another.

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4.1.4.3 Emission to Air
The limit values of emissions to air due to organic solvents are given in national regulations. There is
also the before mentioned EU Directive on the limitation of the emissions due to cleaning processes
(section 1.2.2).
4.1.4.4 Energy
Because of the wide variety of articles and circumstances in which they need to be cleaned, the
energy requirements of cleaning processes vary considerably.
The total energy demand for cleaning includes:
- The energy needed for the production of chemicals
- The energy required for the cleaning process, including recycling and waste treatment.
When a drying stage is required aqueous cleaning processes can be more energy intensive than
those using solvents.
4.1.5 Costs
All companies need to operate in the most cost efficient manner. However, in choosing a suitable
process, costs are only the prime concern after the demands of technical performance, quality of
cleaning, quality and reliability of the cleaned components, operator safety, and environmental
requirements have been met.
Cost analysis should take into consideration all costs connected to the cleaning process including
personnel, health survey, materials, machines and waste disposal.
4.2 Typical Methods
Typical methods for cleaning of components, vessels and pipe work systems used in oxygen service
are summarised in the following section and include:
- Mechanical cleaning
- Chemical cleaning
- Detergent cleaning
- Hot water (steam) cleaning
- Emulsion cleaning
- Solvent cleaning
Appendix B gives examples of cleaning equipment working with aqueous agents and solvents. In
Annexes III - X are given examples of different cleaning procedures.
4.2.1 Mechanical Cleaning
This cleaning method is not used for accurately dimensioned components as the method can cause
uneven material loss. It is usually a preparatory stage in the cleaning procedure, but some processes
such as blast cleaning can be used as a cleaning process provided oils and greases if present are
removed in the process. Critical contaminations which cannot be eliminated by blasting (e.g. markings
carried out with some marking pens) shall be noted and removed by another process.
Selection of the mechanical cleaning method will depend upon several factors, which shall be
considered:
- The extent of contamination.
- The ability of the method to remove the contaminants.
- Unit or component to be cleaned, its shape and the ability to remove all cleaning debris and
cleaning materials.
- The effect of the cleaning materials/procedure relative to the construction materials.
- The surface finish required in/on the unit or component.

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As a final stage in the mechanical cleaning method it is essential that all cleaning materials and debris
are removed by brushing, vacuuming or high velocity blow out using dry oil-free compressed air or
nitrogen or a combination of these.
Mechanical cleaning is not suitable for non-metallic materials.
Mechanical cleaning can take the form of chipping, scraping, flailing, grinding, wire brushing or blast
cleaning.
- Mechanical tube cleaners may be used. These are flexible shaft driven rotating wheel assemblies
that carry out a chipping action on mill scale, etc.
- Wire brushes manufactured from non-ferrous wire are recommended. Carbon steel wire brushes
shall not be used on aluminium or stainless steel surfaces. Any wire brushes previously used on
carbon steel shall not be used on aluminium or stainless steel surfaces. Wire brushing can be
utilised with alkaline solutions to enhance that cleaning method.
- Blast cleaning using abrasive materials such as grit, shot, copper slag, aluminium oxide, glass
bead, sand etc. The blast cleaning method can be carried out using dry oil-free compressed air,
nitrogen or high-pressure water as the carrying media.
This method should not be used on aluminium alloys due to uneven metal loss and embedding of grit
that can occur.
It is recommended that blast-cleaning materials be used on a once through basis unless the material
has been processed to remove any contaminants.
Notes
a) Specifications for materials are given in Section 3, Cleaning Materials.
b) Surface finish alter mechanical cleaning is recommended to be as a minimum Standard N9,
Rugotest No. 3 ISO 2632.
Alternatives Sa 2 1/2 ISO 8501-1 or Swedish Standard SIS 055900.
4.2.1.1 Health and Safety Precautions - Mechanical Cleaning
Mechanical cleaning creates the formation of dust and other particles resulting from the breakdown of
the materials used and also by the removal of surface material from the parts being cleaned. The
particulate matter formed if breathed can be hazardous to health (e.g. quartz dust) and can also
cause serious damage in contact with the eyes.
1) Suitable full protective clothing, including breathing provision, head cover, gloves, apron, face
shield and/or goggles must be worn by the operator and measures to extract excessive dust from
the cleaning area must be employed when necessary.
2) Hoses, nozzles, valves and accessories used shall be of a quality and condition suitable for the
operation being undertaken.
3) National regulations and manufacturers recommendations for ventilation and safe use of blast
cleaning cubicles or rooms and blast cleaning equipment shall be observed.
4.2.2 Chemical Cleaning
Chemical cleaning is a process involving acid or solutions and is used to remove the following alkaline
type of contaminants:
- heavy or tenacious surface adherents
- rust, scale and oxide films
- brazing fluxes
- small amounts of paint, grease, oil film and drawing compounds.
The type of chemical cleaning material selected will depend, in most cases, on the equipment to be
cleaned, the contaminants to be removed and the materials of construction. The manufacturer's

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specification for application of the cleaning agent and necessary safety precautions shall be strictly
observed.
Selection of the chemical cleaning method will depend upon several factors, which shall be
considered:
- Unit or component to be cleaned, its shape, size and ability to remove all residual cleaning
materials.
- Unit or component material and the possible effect of the cleaning material on the materials of
manufacture.
- Extent of material loss which car be permitted by exposure to acids.
- Contaminants to be removed.
- The surface finish required in/on the unit or component.
Acid cleaning is not generally used for the removal of oils and grease and these contaminants, if
present, should be removed by a solvent or by an alkaline solution prior to acid pickling.
Chemical cleaning relates to the cleaning of components by the following alternatives:
- Immersion in a tank containing the cleaning material. Addition of some kind of mechanical energy
is normally required.
- Spraying the equipment with the cleaning liquid.
- Complete filling of the component with the cleaning material. This may be applied to large pieces
of equipment.
- Forced circulation of the cleaning material inside the component, in items such as tubular pieces
of equipment.
The cleaning materials are used as aqueous solutions of either acids or alkaline products. The
solutions prepared will be in concentrations appropriate to the materials used in the construction of
components and the surface condition required. Multiple cleaning operations are sometimes
necessary to treat some metal surfaces, e.g. passivation to retard corrosion.
After the completion of the chemical cleaning operation, by either acid or alkaline solution, all residual
cleaning fluid must be completely drained from the component by flushing with clean oil-free water
and purged.
4.2.2.1 Alkaline Cleaning
This cleaning method is normally carried out as a chemical cleaning process to remove oils and
greases, with a caustic solution at elevated temperature, in the range of 38°C to 82°C (100°F to
180°F), dependent upon solution concentration.
Caustic solutions are made up from powders, crystals or concentrated solutions. All are water-soluble.
Other chemicals with functions like water softening, corrosion inhibition and wetting are often added.
The manufacturers specification for application of the cleaning agent shall be strictly observed.
After cleaning, all components shall be thoroughly rinsed using oil-free water, preferably hot to aid
drying, unless otherwise specified by the supplier of the chemical materials. This is particularly
important for copper, copper alloys and stainless steel in order to avoid the risk of stress corrosion.
4.2.2.2 Acid Cleaning
This is normally carried out with an aqueous solution of acids at ambient temperature. Phosphoric
acid cleaning solution car be used for metals, for the removal of oxides, light rust, light soils, fluxes
and certain protective coatings.
Hydrochloric acid solutions car be used for carbon and low alloy steels only. This solution will remove
rust, scale, oxide coatings and will strip chromium, zinc and cadmium plating. It shall not be used on
stainless steel and brass, which may as a result suffer stress corrosion.

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Hydrochloric and nitric acid solutions require the use of inhibitors as the solubility of metal oxides in
the solutions results in corrosive attack on the base metal.
Following pickling of ferrous surfaces using the above methods, passivation by use of phosphoric
acid, sodium nitrite or phosphate treatment is necessary to prevent flash rusting.
Chromic and nitric acid solutions car be used for cleaning aluminium, copper and their respective
alloys. These solutions in themselves are not adequate cleaning agents, but are regarded as
de-oxidisers for brightening metals dulled by alkaline solution cleaning. Nitric acid solution in
combination with copper and copper alloys produces toxic fumes, and therefore good ventilation is
essential.
The manufacturer's recommendation regarding solution concentration, time and temperature shall be
followed implicitly. Acid solutions should not be used unless their application and performance are
known and have been discussed with the material supplier.
After cleaning, all components shall be thoroughly rinsed, using flowing oil-free water, preferably hot
to aid drying, unless otherwise specified by the supplier of the chemical materials. Special care should
be given to carbon and low alloy steel components.
4.2.2.3 Notes on Alkaline and Acid Cleaning
a) Advice on aqueous acid and alkaline solutions will be found by reference to Section 3 (Cleaning
Materials).
b) Completion of the flushing operation can be assessed by monitoring the outlet water pH value or
conductivity relative to the clean inlet water.
c) Pumps, hoses, bulk tanks, piping and valves used for acid cleaning shall be acid resistant and
compatible with the solution being used.
d) Contaminated cleaning agents and residues must be stored and disposed of according to
manufacturer's recommendations. Local and national regulations shall be observed.
4.2.2.4 Health and Safety Precautions - Acid and Alkaline Cleaning
1) Eye and skin contact with acid and alkaline chemicals should be avoided as bums or serious skin
disorders can result. The breathing of fumes caused by the reaction of the chemicals with the
metals being cleaned should also be minimised. Chemical cleaning agents shall only be used
when their application, performance and health implications are fully understood and the
manufacturers recommendations are complied with.
2) Suitable protective clothing, gloves, apron or sometimes overall suits, face shield and goggles
must be worn by the operator whilst carrying out chemical cleaning operations.
3) Chemicals shall only be carried using suitable closed containers.
4) When acid cleaning in enclosed vessels special precautions need to be taken due to the
formation of inflammable hydrogen gas or toxic fumes resulting from contact of some acids with
the metal surfaces.
5) Acids shall always be slowly added to water when preparing aqueous solutions. Never use the
reverse sequence.
6) Acids and alkalis must never be disposed of directly into the drainage system. For further advice
on environmental considerations and disposal methods refer to IGC Technical Note 515/95.
4.2.3 Solvent Cleaning
This cleaning or degreasing method has to a great extent been replaced by other methods because of
safety and environmental reasons. In certain situations where other cleaning methods cannot be
applied, solvent cleaning may be considered.
The method is suitable for use with all metals; for use on aluminium refer to paragraph 2.2.3.5 item 7
and for non-metallic to paragraph 2.2.3.4. Item b.
Before starting a cleaning operation a reference sample of fresh clean solvent shall be retained. This
sample will be used as a base reference. At intervals throughout the procedure, samples of used
solvent shall be taken. These can be compared with the reference sample to determine the level of

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contamination and the cleaning procedure continued until the acceptance standard of cleanliness is
reached.
Methods of determining contamination can be by comparison of colour to reference sample,
fluorescence under ultra violet light, by analysis, or by evaporation. (See Section 4 Inspection). Glass
bottles are recommended to be used for containing check samples.
Due to the potential hazard caused by solvents in contact with oxygen, after the completion of any
method of solvent cleaning, all residual cleaning fluid must be totally removed from the components.
An assessment of the component or system to be cleaned shall be made to ensure there are no pipe
or other dead ends or pockets present from which it will be difficult to completely drain or blow out the
solvent. If not, then this method shall not be used, or alternatively the system can be modified to
accommodate this method. The component shall be thoroughly drained, purged, and dried with warm,
dry, oil-free air or nitrogen. Small components may be air dried only, if appropriate. A method of,
checking that residual solvents have been eliminated is by using a commercially available vapour
detector/analyser on completion of the purge and drying process following cleaning.
The unit used comprises an aspiration pump to measure the sample volume using disposable,
calibrated, colorimetric detector tubes. This test can be supplemented by carrying out a sniff test when
it is considered to be completely purged of solvent vapours.
Solvent cleaning methods used are described in the following sub-sections. However, components of
a simple shape and with all surfaces accessible may be cleaned by wiping with a solvent using a
lint-free clean cloth and followed by drying.
Potential users should determine whether the solvent has been declared acceptable by
national authorities. Solvents shall only be used in stabilised form.
4.2.3.1 Immersion in Solvent Method
Cleaning of individual components can be effected by immersing the component in a tank of solvent,
at ambient temperature, and applying a means of agitation.
Disassembled parts can be cleaned by this method. The process can be improved by the use of an
ultrasonic generator. Some methods utilising solvents are described in Appendix B Section 4.
4.2.3.2 Forced Circulation Method
Cleaning by forced circulation of a flow of the solvent liquid through the component can be carried out.
This is done with the solvent at ambient temperature.
The duration of cleaning by circulation shall be continued, using clean solvent, until the used solvent
emerges from the component as clean as the solvent pumped in.
This method is a highly specialised cleaning procedure and is applied principally to assemblies, which
cannot be disassembled, large size components and prefabricated circuits, pipe works, etc. The use
of this method is, however, limited by the ability of the solvent to reach contaminants present in a
complex system and its subsequent complete removal.
4.2.3.3 Vapour Phase Method
Solvent vapour phase cleaning of components consists of the removal of contaminants by the action
of continued condensation of solvent vapour on the component surfaces.
The procedure requires that the equipment or component is colder than the solvent boiling point.
A significant advantage of solvent vapour phase cleaning is that re-vaporised solvent is always clean
and contaminants remain in the evaporator liquid section, which will require periodic cleaning out.
A description of the method for one type of equipment is given in Appendix B.

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4.2.3.4 Notes on Solvent Cleaning
a) Advice on suitable solvents will be found by reference to Section 3 (Cleaning Materials).
b) Some plastic materials, including polyvinyl chloride (PVC) and poly-methylmetacrylate (PMMA)
should not be used as containers as the plastics can be extracted by the solvent and be
deposited on the component being cleaned. Similarly, rubber and neoprene are also affected.
Therefore, products manufactured from these materials shall not be cleaned with chlorinated
solvents.
Polytetrafluoroethylene (PTFE) is satisfactory for use with chlorinated solvents and is the most
frequently used material. Generally, non-metallic materials require confirmation of acceptability before
use.
4.2.3.5 Health and Safety Precautions - Solvent Cleaning
Solvents are generally toxic and may act on the human body through inhalation, penetration of the
skin and ingestion (see exposure limits for some solvents in Table 1). Some, such as
dichloromethane, trichloroethylene and tetrachloroethylene are classified as suspected to be
carcinogenic.
Solvent cleaning agents shall only be used when their application, performance and health
implications are fully understood and the manufacturer's recommendations are complied with.
1) Vapours from some solvents are a powerful anaesthetic. Inhaled in small quantities it will cause
drowsiness. In large quantities the vapour can cause unconsciousness and fatality. National
regulations provide measures to control use of these products.
Emission to the atmosphere has to be considered and kept to a minimum level and of course in
accordance with legislation.
Care must be taken that adequate ventilation is provided in areas utilised for solvent cleaning to
prevent people breathing excessive amounts of solvent vapour or the products of decomposition.
In solvent cleaning operations outdoors, it may be possible to locate the' working area to keep
people up wind of solvent handling.
Receptacles for the solvent shall not be left in working areas without lids or caps fitted, and shall
be suitably labelled.
To avoid exposure above permitted levels solvents shall not be removed from components by
blowing dry in confined spaces.
2) Some solvents may decompose to form very toxic gases, e.g. phosgene in the presence of heat
sources (> 200°C) or ultra violet rays.
Some mixtures are readily ignited with increased pressure and/or oxygen content.
Most solvent vapours are capable of creating an explosive mixture at certain concentrations with
air or oxygen.
It is important to ensure that parts to be welded or heated shall be totally free of solvent.
Smoking and the performance of any operations involving the use of flame, arcing or other source
of heat higher than 200°C shall be prohibited on premises where vapours of halogenated solvents
are present. Exposure of the solvent to daylight over a prolonged period may also cause
decomposition of the material.
Do not heat solvents above the allowable temperature. This temperature shall be checked with
the solvent supplier or with other relevant information like the Material Safety 0Data Sheets.
Do not use chlorinated solvents for cleaning closed tanks or other elements where it is not
possible to ensure total removal of the solvent.
3) Characteristics of solvents, toxicity, occupational exposure limits etc. will be found by reference to
Section 3 (Cleaning Materials) and Table 1.

11
AIGA 012/04
4) Due to the harmful effects skin contact must be avoided by using nitrile gloves, apron and safety
glasses with side shields or facemask. Note that polyvinyl chloride (PVC) gloves are only suitable
for short periods of use.
5) Solvents shall only be carried using suitable closed containers.
6) Manufacturers of solvent cleaning plants and associated equipment, including ultrasonic methods,
issue recommendations on safe operation procedures. Operators shall comply with the
manufacturer's advice. Enclosed systems shall always be equipped with pressure relief devices
and a pressure gauge. Heating of solvents shall always be by indirect methods.
7) Aluminium and its alloys without the protective oxide film react vigorously with certain solvents to
produce acid vapour, which is both toxic and corrosive. This particularly occurs on particles of
aluminium such as swarf or grains from machining or cutting processes. When using solvents to
clean aluminium; the following should be observed:
- Use only clean solvent that contains the correct level of inhibitors for aluminium or light alloys.
- Components should be placed gently into the degreasing tank to avoid rupturing the
protective oxide film.
- Newly machined aluminium and aluminium alloy components should be retained in the
normal atmosphere in order to create an oxide film prior to being degreased.
- Ensure that the material being cleaned is free from particles such as swarf or dust.
- Solvents shall not be kept in contact with aluminium for extended periods. Alter cleaning
remove solvents as quickly as possible.
4.2.4 Detergent Cleaning
This method relates to the cleaning of plant components, vessels, piping systems etc., either
externally or internally.
Detergent cleaning is done in water solutions containing chemicals with different functions like dirt
solvency, dispersion, water softening, corrosion inhibition and wetting. It is normally performed in an
alkaline environment, the higher pH value, and the better the degreasing efficiency.
Detergents are supplied in solid or concentrated liquid form. They are prepared for use by mixing with
hot water to form aqueous solutions. Prepared solutions can be pumped, re-circulated or jetted onto
or through the component. They are well suited as cleaning agents in ultrasonic baths.
The degreasing strength of detergents is as good as that of the solvents.
Aqueous systems have few problems with worker safety compared to most other solvents. They are
not flammable or explosive and toxicity is low for most formulations.
The omission to water is the main environmental question to consider in aqueous cleaning.
Dependent on local regulations, type of contaminants and detergent, concentrations, pH etc., the
waste from water based detergent cleaning might be disposed of into the sewer for which a permit or
consent may be required.
4.2.4.1 Notes on Detergent Cleaning
a) Before use, ensure that detergent chemicals used are suitable as some non-metallic materials are
not compatible with the detergent chemicals or may absorb the fluid.
b) Advice should be sought and followed from the detergent manufacturer regarding solution
concentration, the materials it is suitable for, and safety precautions required
c) For details with narrow cavities, the cleaning stage should be of the immersion type, where all
parts of the contaminated details come in contact with the cleaning agent. Spray cleaning
machines like a normal dishwasher is therefore an unsuitable alternative.
d) Aqueous cleaners have higher surface tension compared to organic solvents and therefore
difficulty in penetrating into threads and narrow cavities. To get a good contact between cleaner
and contaminated details, some kind of mechanical energy should therefore be added. This
mechanical energy might be provided by air agitation, jet flushing or ultrasonic. Rotation may be
necessary to ensure elimination of air pockets.
e) Increased temperature improves the cleaning. The cleaning bath should therefore be equipped
with a heating device and temperature control.

12
AIGA 012/04
f) An aqueous cleaning system requires a subsequent rinsing step. It is important that all cleaning
products, grease as well as cleaner residues, are removed. The rinsing step must be performed
immediately alter the cleaning stage, before the cleaned details have dried. The higher rinsing
temperature, the better. The final rinsing must be done with clean water.
g) When water based cleaners with water rinsing are used, there is a risk for corrosion. Freezing of
remaining water may also be a problem in certain installations.
The system then needs to be carefully dried out. A purge of dry oil free air or nitrogen (min -40°C
dew point) might be used. A final rinsing with alcohol (e.g. isopropyl alcohol) after water rinsing for
improved water removal- might be used if the flammability risks can be controlled.
Care should be taken when drying out the system, not to rely purely on exit gas dew point
readings. Prior to commencing drying, drain points should be checked to ensure that all
freestanding liquid has been removed. Blowing through with dry oil free air or nitrogen at ambient
temperature normally takes a very long tune to achieve the necessary dryness.
h) It is important that water-containing detergent is not directed to an oil/water separating system, as
it will prevent such a system operating correctly.
4.2.4.2 Health and Safety Precautions - Detergent Cleaning
1) Operators carrying out detergent cleaning shall wear goggles or facemask and gloves.
2) Skin contact with detergent chemicals should be avoided as serious skin disorder can result.
3) Materials used for pumps, hoses, valves and accessories shall be compatible with the selected
detergent to be used.
4) The manufacturer's product information and material safety data sheets must be carefully studied.
4.2.5 High Pressure Hot Water (Steam) Cleaning
This method can be carried out using commercially available specialised equipment (one type
described n Appendix B section 3.1) for complete external and internal cleaning of major plant parts
and pipes with internal diameters down to approximately 10 mm. It removes oil and grease as well as
welding and brazing residues and other contaminants. The addition of detergents can improve the
performance of this cleaning method. (One typical application is described in Appendix D)
The cleaning medium is heated potable water or water/steam which is jet sprayed onto the work
pieces at a pressure of up to 180 bar. If a large flushing effect is required water only is used. The high
temperature and the high pressure ensure that all contaminants are removed from the surface and
washed away.
This method is not recommended for use on electrical equipment due to possible ingress of moisture.
Due to the jet being at high temperature and pressure care must be taken to ensure suitability of
equipment for cleaning by this method.
Cleaning with high-pressure water demands an ample water supply, and good wastewater facilities.
Wastewater must be directed to the foul sewer and not discharged directly to surface water.
4.2.5.1 Health and Safety Precautions - High Pressure Hot Water Cleaning
1) Protective clothing, gloves, apron, eye and face protection are recommended to be worn by the
operator whilst carrying out high pressure cleaning.
2) Follow the equipment supplier’s instructions for the use and handling of the cleaning lances. Both
hands shall always be on the handles and grips of the spray lance.
3) It is strictly prohibited that high pressure cleaning is used for personal cleaning.
4.2.6 Emulsion Cleaning
Emulsion cleaning is a process for removing heavy contaminants like oil and grease from the surface
of parts. Oxides cannot be removed.
Emulsions are used for the same type of parts as water based detergent cleaners. The applied
methods and used equipment is also similar to detergent cleaning.

13
AIGA 012/04
In an emulsion, a solvent is emulsified in water by surface-active agents. The cleaning 'is effected
mainly by the solvent in the droplets whereupon the cleaner together with the cleaning products are
removed by water rinsing. The cleaning efficiency can be increased by adding alkaline agents and
surfactants (tensides). The cleaning action of the emulsion then combines the advantages of both
detergent and solvent cleaning.
In other emulsion systems, water free solvents with added emulsifiers are used. The cleaning has
then to be considered as solvent cleaning. The emulsifying of the solvent and cleaning products takes
place first when water is added in the subsequent rinsing stage.
The concentration of dissolved contaminants in the cleaner can normally become considerably higher
for emulsions compared to aqueous systems before the cleaning effect diminishes. The penetration
into narrow hollows is better than for pure aqueous systems.
The cleaning is normally performed at ambient temperature.
The impact on the working environment from emulsion cleaners originates from vaporised solvent.
This impact is however smaller compared to pure solvent systems because of the low solvent
concentration and low solvent vapour pressure.
4.2.6.1 Notes on Emulsion Cleaning
a) Before use ensure that emulsion chemicals used are compatible with all metallic and organic
materials.
b) The cleaning must be followed by careful rinsing to prevent contamination from re-depositing on
the surface. The surface must not be allowed to dry between the cleaning and rinsing phase.
The rinsing is especially important when high boiling petroleum derived solvents are used in the
emulsion. A thin film of high boiling hydrocarbons may otherwise remain on the details alter
cleaning, which might be a safety risk in oxygen service.
c) As with pure water based cleaning, the cleaned parts need to be dried alter rinsing. A purge of dry
oil free air or nitrogen (min -40°C dew point) in might be used. After water rinsing, a final rinse
with alcohol (e.g. isopropyl alcohol) may be used to improve water removal if flammability risks
can be controlled.
d) The circulation and cleaning of spent cleaning liquid is relatively complicated in emulsion systems.
Emulsified oil can be removed by ultra filtration, chemical decomposition, micro filtration,
adsorption or biological treatment, but a lot of the chemicals in the cleaning liquid are normally
lost in these operations.
The used contaminated cleaner must be disposed of as a waste in fine with local or National
Regulations.
See also Notes on Solvent Cleaning (section 2.2.3.4) and Notes on Detergent Cleaning (section
2.2.4.1 ).
4.2.6.2 Health and Safety Precautions - Emulsion Cleaning
When using emulsions, the risks with the applied solvents and other chemical components must be
carefully considered.
1) Advice shall be sought and followed from We emulsion manufacturer regarding contents of
chemicals, solution concentration, the materials suitable for and the safety precautions required.
2) Materials used for pumps, hoses, valves and accessories shall be compatible with the selected
emulsion to be used.
3) Emulsions are considered non-flammable in bulk form but can be flammable in an aspirated or
mist conditions. Proper equipment design is essential to minimise risk from flammable mists.
Some formulations can auto-oxidise into an undesirable condition.
4) The equipment including venting system must be explosion proof because of exposure to
vaporised solvent.
5) Inhalation is the primary safety concern, but the degreasing of the skin must also be considered.

14
AIGA 012/04
Operators carrying out emulsion cleaning shall wear facemask with appropriate filter or goggles
depending on the composition of the emulsion and on the operation conditions.
Skin contact with emulsion chemicals should be avoided as serious skin disorder can result.
See also Safety Precautions for Solvent Cleaning (paragraph 2.2.3.5) and Safety Precautions for
Detergent Cleaning (paragraph 2.2.4.2).
4.2.7 Rinsing
The purpose of rinsing is to remove remaining cleaning agents and emulsified contaminants.
This operation is performed after acid, alkaline, detergent and emulsion cleaning.
After the cleaning stage, the parts are immediately transferred to rinsing, which must be done before
the parts have dried.
The rinsing operation can take place in one or several stages by immersion, spraying or a
combination of these methods.
In immersion baths, some type of agitation is necessary. This might be accomplished by using an
impeller, water jets, air injection or movement of the parts. Ultrasonic energy can also be used to
improve the rinsing efficiency.
Spray rinsing can be used for details with smooth surfaces without cavities where all parts can be hit
by the rinsing liquid.
High rinsing temperature improves the rinsing efficiency. Hot rinsing water will also heat up the
cleaned parts, which saves time in the subsequent drying stage.
Cleaning agents with high alkalinity are more difficult to rinse away than other cleaners. Raised
temperature may then be required.
The final rinsing must be done with clean water.
The removal of liquid from the details after rinsing can be enhanced by blowing off with nitrogen or
oil-free pressurised air.
It is extremely important to perform the rinsing operation very carefully to ensure that all cleaning
products, cleaner residue as well as contaminants, are completely removed. The supplier of the
cleaner should be consulted when the rinsing conditions are decided.
4.2.8 Drying
Drying is applied to prevent corrosion and to speed up the total cleaning process in processes where
water rinsing is used. This drying operation is often the most time consuming stage in the overall
cleaning process. It may be performed in separate drying equipment or as an integrated stage in an
automated cleaning apparatus.
Drying is accomplished either with hot gas (convection) or radiation.
In hot gas drying, the necessary energy for water vaporisation is transported to the goods by the hot
gas itself.
In drying by radiation, the walls of the drying chamber are heated up, emitting heat radiation, which in
turn heats up the goods enough for water vaporisation.
The gas temperature is often in the range of 70150°C for hot gas drying. In drying, using radiation, the
parts are heated to a temperature of 150-200°C. This temperature has to be considered when drying
polymeric materials.

Porous parts and parts with small or narrow cavities are difficult to dry.
15
AIGA 012/04
The drying process can be hastened by immersing the wet parts into a solvent miscible with water
(e.g. alcohol), which lowers the surface tension and causes the water droplets to flow out into a thin
film.
The humidified gas must be continuously vented from the drying chamber, as evaporation will cease
when the gas is saturated with water vapour.
4.2.9 Removal of Cleaning Agent
Purging can be considered complete when the cleaning agent cannot be detected by appropriate
methods in the gas venting from the vessel, piping or component being purged.
If the odour of cleaning agent is detected in the vicinity of the effluent purge gas, the equipment
requires additional purging.
If the used cleaning agent is odourless, a leak detector specific for the cleaning agent has to be used.
In the specific case of aqueous cleaning agent, the sole hazard is the deposit of the cleaning agent,
which could be flammable.
This situation cannot be possible if the choice of detergent insures that even the traces of solid
residues of dry detergent are not flammable.
5 Cleaning materials
This section gives guidance on materials, which are suitable for use as cleaning agents, limits of
application and precautions to be taken in using the materials. Most cleaning materials are not
completely compatible with oxygen. Special care shall be given to the properties of the cleaning agent
regarding flammability, toxicity, corrosion effect, and environmental impact.
Tables 1 to 3 provide recommended materials. Materials used for pre-cleaning processes and final
cleaning are included. Alternatives may only be used with reservation when the recommended
materials are not obtainable and with particular precautions.
Precautions must be taken when using cleaning materials according to the Material Safety Data
Sheets (MSDS), the manufacturers recommendations, different local or national regulations and the
rules of the supplier. Other general safety precautions to be taken are detailed in Section 2. Parts of
equipment that are not compatible with the cleaning agent shall be removed or isolated.
5.1 Mechanical Cleaning Materials
The following materials are recommended for use for mechanical cleaning.
5.1.1 Blast Cleaning
Materials used for blast cleaning operations and their carrier shall be free from oil and grease.
Blast cleaning of rough castings, forgings, plates, vessels, piping etc. can be carried out using the
following materials:
- Copper slag particles
- Aluminium oxide
- Glass beads in high pressure water or dry air
- Sand
Metallic shot (powder or grains of cast iron, iron, steel etc.) may be used. However, it is not
recommended as in certain conditions it is capable of burning or initiating ignitions in oxygen. It shall
therefore only be used if complete removal can be assured.

5.1.2 Wire Brushes
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AIGA 012/04
Wire brushes manufactured from stainless steel, copper, brass or bronze wire are recommended.
Brushes shall be clean and in a good condition.
5.2 Chemical Materials
Chemical cleaning materials are included in the following paragraphs under the types of chemicals:
- Alkaline Solutions
- Acid Solutions
- Solvents
- Detergents
- Emulsions
Tables 1 to 4 provide examples of application of the chemicals included. The safety precautions are
detailed together in paragraphs 2.2.2.4, 2.2.3.5, 2.2.4.2 and 2.2.6.2.
5.2.1 Alkaline Chemicals
Aqueous solutions of the following alkaline chemicals, often as mixtures, may be used as cleaning
materials.
Sodium hydroxide: NaOH (caustic soda).
Sodium carbonate: NazC03 or sodium bicarbonate, NaHC03 (buffet solution)
Sodium phosphate: Na3, Po4 (water softener, emulsifier and buffet).
Sodium silicates: NaSi04 (emulsifiers and buffets).
Refer to Table 2 for details of recommended alkaline materials for the metal involved and reason for
cleaning. Other treatments required in addition to water rinse and drying are shown.
5.2.2 Acid Chemicals
Aqueous solutions of acids are used as chemical cleaning materials for the following applications:
- chemical pickling
- temporary corrosion protection (passivation)
The acid chemicals used depend on the nature of the contaminant to be removed, the metal to be
cleaned, and the application. Refer to Table 3 for details of recommended acid solutions for the
material involved and the type of cleaning required. Other treatments required in addition to water
rinsing and drying are shown.
Acid cleaning of steel components is normally preceded by degreasing using solvent or alkaline
treatments to remove oil or grease contaminants.
Chemical pickling using aqueous solutions of acids is applied to vessels or pipe fabrications made of
carbon or low alloy steels and removes rust, scale and certain protective coatings. The operation shall
be completed by rinsing with a neutralising product or with running clean oil free water until the rinsing
water outlet pH is neutral.
The following acid solutions are used for this application.
Nitric acid, HN03
Hydrochloric acid, HCl
Sulphuric acid, H2S04
Chromic acid, H2Cr04
Hydrofluoric acid, HF (stainless steel only)
Phosphoric acid, H3P04

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AIGA 012/04
Chemical passivation is a treatment used to provide temporary corrosion protection of carbon and low
alloy steel surfaces, which have been pickled. Phosphoric acid (H3P04) or sodium nitrite solutions are
used for this treatment. After treatment, the equipment shall be completely washed, drained and
dried. Surfaces treated in this way have a uniform grey colour, occasionally with some highlights of a
reddish brown colour due to deposits of salts of the passivation products. Any blackish deposits left
on the surface which are slightly sticky to touch, are an indication that draining after passivation has
been incomplete. Whitish surfaces with a tendency to be floury indicate incomplete drying.
Acid solutions that attack the base metal or react with contained moisture may require the addition of
inhibitors.
There are commercially available products and solutions designed either for de-scaling or for
anti-corrosive protection, or to fulfil both of these functions simultaneously. The exact compositions of
these products are not always provided. They should not, therefore, be used unless compatibility tests
have demonstrated the safety of the
5.2.3 Solvents
Some chlorinated solvents are still acceptable and established alternatives include hydro
chlorofluorocarbons (HCFCs), aliphatic hydrocarbons and some specialised constant boiling blends.
The use of HCFCs should only be regarded as a transition alternative due to the possibility of their
phasing out in the future.
Chlorinated solvents offer an advantage in that they tend to be usable in conventional degreasing
equipment. A selection of solvents for cleaning oxygen service equipment is listed in Table 1.
Pertinent data that is available on these products is also included.
Although the solvents listed are low in their ozone depleting potential, they are volatile organic
compounds and will, in some cases, also have a global warming potential. This should be taken into
account when considering any investment in cleaning equipment.
In addition to the cleaning ability of the solvent, material' compatibility, toxicity and environmental
issues in the application, and waste disposal aspects must ail be considered when choosing the most
suitable solvent for a given cleaning application. On completion of cleaning it is essential that all
traces of solvent remaining are removed. If necessary, this should be confirmed with appropriate
detection equipment (e.g. halogen leak detector or detector tube for chlorinated solvents). When the
favoured method of cleaning is to use a solvent, its choice will represent a compromise combination of
relevant properties. Solvents used shall be of a stabilised grade of proven suitability.
It is important to ensure that the solvent is compatible with the materials used in the construction of
parts being cleaned. Un-stabilised solvents can cause metal corrosion. The presence of moisture
accelerates the corrosive effects of trichlorethylene and it is therefore essential that care is taken to
maintain the quality of the solvents in use.
Solvent degreasing must be carried out in a well-ventilated area and appropriate personal protective
clothing should be used. The occupational exposure limits/threshold limit values shall be considered.
Any changes of cleaning agent must be accompanied by a rigorous assessment of the risks to health
of those involved in the changed process. Any necessary controls must be established and
information provided to those involved with the changed solvent. This is required by legislation in most
countries.
Flammability is an important safety issue with hydrocarbons.
Alcohol, oil spirits, some solvents and dry residues of aqueous detergents are flammable with oxygen.

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These characteristics of flammability are well known and the use of flammable products for oxygen
cleaning is strongly limited. However if this type of product is used, the procedure for rinsing, purging
and checking has to be carefully qualified.
It shall be ensured that after the complete procedure no residuals of flammable vapour or liquid
remain in the equipment especially in complicated configurations, dead ends etc.
The qualified procedure is specific for a given equipment.
When non-flammable solvents are chosen, hydrocarbon-free grades should be used.
The recycling of solvents and their ultimate safe disposal must conform to national legislative
requirements. Accurate records should be maintained with a view to establishing a mass balance.
Where disposal of spent solvent is required, it will normally be necessary to employ an approved
professional waste disposal agent.
National legislation will normally stipulate the storage and transport requirements. All solvent,
recovered solvent and waste must be clearly labelled. Solvent must never be discharged directly into
drains, sewers or natural watercourses. Checks should be carried out on the purity of solvent that is
reused or has been recovered.
5.2.4 Water Based Detergents
Detergent cleaning is done in water solutions containing chemicals with different functions. It is
normally performed in an alkaline environment, the higher pH value, the better the degreasing
efficiency
Common components in alkaline detergents and their main functions are shown in table 4.
The most important detergent components are the surfactants. They decrease the surface tension of
the water solution, penetrate the organic contaminants and make them disperse as small droplets into
the water solution.
Proprietary synthetic detergents are available for use to clean different polymers, metals and alloys. It
is most important the manufacturer's recommendations are complied with and also the effect on any
non-metallic materials which are present.
5.2.5 Emulsion Cleaners
Emulsion cleaner systems have three main components - water, an organic solvent and surfactants.
They are used in two ways:
- The solvent emulsified in water is applied in a manner similar to standard aqueous cleaners. The
solvent is the main dirt dissolver and the surfactants work principally as emulsifiers.
- Water-free solvents with added emulsifiers are applied in concentrated form and then rinsed with
water. The emulsifying of the solvent and cleaning products takes place first when water is added
in the subsequent rinsing stage.
For safety and environmental reasons, solvents with high flash point and low vapour pressure are
normally chosen. Examples of solvents are different high) oiling hydrocarbons, citrus based terpenes.
(e.g. d-limonene) and pine based terpenes. Other examples are esters (e.g. lactate esters) and glycol
ethers.
Proprietary emulsion cleaners are available to clean different polymers, metals and alloys. It is most
important the manufacturers recommendations are complied with and also the effect on any
non-metallic materials which are present.

5.3 Cleaning Cloths
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AIGA 012/04
Goths used for wiping components or small areas of equipment surfaces shall be clean, lint-free and
free from traces of oil or grease. Cotton, linen or paper re commonly used materials.
5.4 Desiccating Materials
Desiccating materials are sometimes placed in equipment after cleaning to prevent any corrosion, or
other deterioration due to humidity of air that may be present during the period of shipment or storage.
The following may be used:
- alumina
- silica gels
- molecular sieve
- regenerated clays
Certain colour additives may be included in the products to give an indication of the moisture content
5.5 Drying/Purging Gas
The gas used shall be dry air or nitrogen and free from oil, grease and particulate matter. Air is
considered suitable when its content of oil, grease and particulate matter is less than 1 mg/m3 and
dry if its dew point value is equal or lower than -40°C at 1.013 bar. For continuous purging of
equipment, using air, filtered atmospheric air compressed by a non-oil lubricated compressor is
recommended.

Solvent
(trival / common name)
CHLORINATED SOLVENTS
Dichloromethane
(Methylene Chloride)
Chemical
formula
Table 1: Industrial solvents 1
Occupat.
Exposure
Limit 2 ppm
Solvent
power Kauri-
butanol
Index 3
20
Flammable.
limits in %
CH2Cl2 100 136 11.7-68 39.8
(1.5)
Trichloroethylene C2HCl3 100 130 7.5-95 86.9
(2.7)
Tetrachloroethylene
(Perchloroethylene)
C2Cl4 50 90 10-65 120.9
(7.1)
Boiling point (°C)
(Re. evap. time) 5
AIGA 012/04
ODP 6
HGWP 7
POCP 8
ODP zero
HGWP
nil
POCP 0.9
ODP zero
HGWP
nil
HYDROCHLOROFLUOROCARBONS (HCFCs) Also used in blends with other solvents
2,2-Dichloro 1,1,1
trifluorothane (HCFC
123)
1,1-Dichloro -1fluoro-ethane
(HCFC 141b)
3,3-Dichloro-1,1,1,2,2
pentafluoropropane
(HCFC 225 ca)
1,3-Dichloro-1,1,2,2,3
pentafluoropropane
(HCFC 225 cb)
POCP 7
ODP zero
HGWP
nil
POCP 0.5
C2HCl2F3 none 2 ODP 0.02
HGWP
0.02
C2H3Cl2 F 61 5.6-17.7 4 32 9 ODP 0.11
HGWP
0.1
C3HCl2F5 34 51.1 ODP 0.025
C3HCL2F5 30 56.1 ODP 0.033
MISCELLANEOUS SOLVENTS
Acetone C3H60 750 3.0-11 4 56.5
Isopropanol C3H80 400 2.5-12 4 82.5
Methyl ethyl ketone C4H80 200 1.8-11.5 4 79.6
Natural oils 10
Notes on Table I
1. Potential users should determine whether the solvent has been declared acceptable by national
authorities. Solvents shall only be used in stabilised form.
2. Occupational exposure limits are those cited in the UK by the Health & Safety Executive in the
1994 edition of their annual publication. The figures refer to a time weighted average for an 8-hour
day. The terminology used varies in different countries, e.g. threshold limit values (TLV) in
Belgium, France, Italy, USA, MAK/TRK in Germany and MAC in the Netherlands. The values
used should always be those cited in the National regulations relating to the country in which
operations are being conducted.
3. The Kauri-butanol index (KB) is a measure of the relative solvent power of the chemical. It
corresponds to the volume of solvent which when added to a solution of kauri gum in butanol
causes commencement of cloudiness in the solution. The better the product as a solvent, the
higher the KB value.
4. The figures quoted are the lower and upper flammability limits expressed as a percentage by
volume of the vapour in air.
5. The relative time of evaporation is the ratio between the evaporation time of the liquid concerned
and that of diethyl ether at a temperature of 20±2° C and a relative humidity of 55±5%.
6. Ozone depleting potential (ODP) is expressed relative to CFC- 11 (Fluorotrichloro-methane)= 1.
7. Halocarbon global warming potential (HGWP ) is expressed relative to CFC -11 =1.
8. Photochemical ozone creation potential (POCP) is a relative measure of the ability of volatile
organic compounds to enter into reactions that lead to poor air quality due to the formation of low
altitude ozone. The base is taken as ethylene = 100.
9. Not suitable for cold cleaning.
10. e.g.: proprietary orange oils/mineral spirits. They are typically of high boiling point (200°C) and low
volatility.

Table 2: Alkaline chemical cleaning materials
(Also applicable to Alkaline Detergents)
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AIGA 012/04
METAL USED FOR CLEANING CHEMICALS OTHER TREATMENT
Carbon, Low
Alloys Steels
and 9% Nickel
Austenitic
Stainless Steel
Copper and
Alloys
Aluminium and
Alloys
Removal of heavy soil,
grease and oil
Removal of heavy soil,
grease, light oils and
cutting fluids
Removal of greases,
lubricating oils, drawing
compounds, oxides,
metallic particles or other
contaminants
Removal of brazing fluxes Hot water
Removal of greases, oils
and oxides
Mixtures of Sodium
hydroxide, carbonates,
phosphates and silicates
and synthetic wetting agents
Mixtures of Sodium
hydroxide, carbonates,
phosphates and silicates
and synthetic wetting agents
Mixtures of Sodium
hydroxide, polyphosphates,
silicates, carbonates, wetting
agents
Etching: Mixed solution of
sodium hydroxide and
sodium phosphate
Non Etching: Mixed solution
of sodium carbonate, sodium
silicate, sodium
pyrophosphate and sodium
metasilicate
Solutions should not be
allowed to dry on the
component, they must be
thoroughly rinsed away
before passivation
(See Note 3)
Usually bright dipped in
dichromate chromic acid
solution (See Note 3)
Dilute nitric acid dip to
remove deposits remaining
after alkali dipping.
Note:
1) The manufacturers specification for application of the cleaning agent shall be strictly observed.
2) After cleaning using alkaline chemicals, all components shall be thoroughly rinsed, using flowing
oil-free water, preferably hot to aid drying, unless otherwise specified by the supplier of the
cleaning materials.
3) There is a risk of stress corrosion attack unless the components have all chemical cleaning
materials removed.

Table 3: Acid chemical cleaning materials
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METAL USED FOR CLEANING CHEMICALS OTHER TREATMENT
Carbon and low
alloy steels
Removal of scale and
oxide films (pickling)
Inhibited hydrochloric acid or
sulphuric acid and wetting
agents
Removal of light rust
Citric acid or sulphuric and
phosphoric acids
Cast Iron Removal of oxides Chromic acid and sulphuric acid
Austenitic
Removal of oxides, Chromic acid and sulphuric acid
tarnish and scale and and hydrofluoric acid, or nitric
Stainless Steel metallic deposits / and hydrofluoric and
contaminants phosphoric acids
Copper and
Alloys
Aluminium and
Alloys
Note:
Removal of scale and
oxide (pickling)
Removal of oxides
(Etching Cleaning)
Hydrochloric or sulphuric acid
Chromic / sulphuric acid,
Nitric / Hydrofluoric acid,
Phosphoric / chromic acid
Dilute alkali dip to
neutralise acid followed
by passivation
treatment using sodium
nitrite or phosphoric
acid
Light scrubbing action
helpful
Nitric acid solution used
to brighten
Sulphuric and nitric and
hydrochloric acids are
used to brighten
Nitric / phosphoric acid
for chemical
brightening.
1) The manufacturers speci8cation for application of the cleaning agent shall be strictly observed or
the properties of the metals can be impaired (e.g. hydrogen embrittlement).
Time/temperature/concentrations are very important.
2) Alter cleaning using acid, all components, except carbon and low alloy steels, (see 3.2.2) shall be
thoroughly rinsed, using flowing oil-free water, preferably hot to aid drying, to avoid corrosion risk,
unless otherwise specified by the supplier of the cleaning materials. Some components require
treatment using neutralising solutions after certain cleaning procedures

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Table 4: Common components in alkaline detergents and their main function
Main function Examples of common components
Dirt Dissolvers
PH Raising Agents
Dispersers
Softeners
Corrosion inhibitors
Wetting Agents
Sodium Hydroxide
Potassium Hydroxide
Sodium Carbonate
Sodium Silicate
Surfactants (Tensides)
Sodium Silicate
Polyphosphates
Polyphosphates
Borates
Glyconates
Sodium Silicate
Borates
Amines
Polyphosphates
Glyconates
Surfactants (Tensides)

6 Inspection methods and acceptance criteria
6.1 Introduction
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It is essential that equipment supplied for use in oxygen service comply with the users specified
cleanliness requirements. Agreement on the manufacturer's detailed quality control procedures and
standards is required between the manufacturer and the user.
Inspection by the user at the manufacturer's location is desirable. Initial and periodical auditing of the
cleaning method and cleanliness control provisions of the manufacturers' workshops or site
installations, cleaning and quality control provisions and its use, is necessary.
6.2 Inspection Methods
Various methods exist for determining the cleanliness of the cleaned parts. It is necessary that the
method selected complements the cleaning method used and shows whether the acceptance criteria
are achieved.
This section covers the most practical and effective methods available. Qualified inspectors with the
necessary training and relevant industrial experience are needed for this activity.
Parts that are inaccessible for inspection after assembly may require to be disassembled or inspected
prior to assembly.
If an inspection reveals the presence of non-acceptable contamination, with oil or grease, residues of
cleaning agent, or particles, the item of equipment must be partially or even completely re-cleaned.
Persistent rejection requires a re-evaluation of the cleaning methods used and of the quality control
provisions.
The usual inspection methods are:
- Direct Visual Inspection with White Light
- Direct Visual Inspection with Ultra Violet (U.V) Light
- Wipe Test
- Solvent Extraction
- Water Break Test
- Chromatographic and Spectrometric Methods and other Special Methods.
The method(s) selected depends on the required cleanliness.
6.2.1 Direct Visual Inspection with White Light
This is the most simple inspection method used to detect the presence of contaminants on equipment
with accessible surfaces. This method will detect without magnification small particulate matter, dust,
oil, grease and moisture in amounts, which could be tool high. It shall be used in conjunction with
other methods.
It is important to have a sufficiently bright level of artificial or natural daylight.
Acceptance criteria:
Visual inspection of the surfaces under bright light shall show no evidence of:
- organic material such as oil, grease, paint, etc.
- cleaning agents including detergents
- rust and loose scale, weld spatters, particles dust, fibres or Other foreign matter
- flux residues from welding, brazing or soldering
- moisture

6.2.2 Direct Visual Inspection with UN. Light (Black Light)
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An UV-light with a wavelength of about 0,37 um is used in dark or near darkness at a distance of
about 10 to 20 cm from the surface or piece being examined. Many common but not all hydrocarbons
or organic oils fluoresce under UV-light. The method might indicate fluorescent areas to be further
inspected by other tests such as wipe or solvent test.
The intensity of the fluorescent reflection from various oils is very different. For some vegetable and
chemical oils it is zero. Therefore it is important not to rely solely on the result of this test in evaluating
the cleanliness of equipment cleaned for oxygen service.
Note that excessive exposure to direct or reflected ultraviolet light can cause eye and skin damage
and therefore care must be taken when it is being used and lamp manufacturers instructions shall be
complied with.
Acceptance criteria:
This qualitative method can better be used, if the contaminating oil and its reflecting capacity are
known. The method should be used in conjunction with a quantitative test. A low specified amount of
small particles can be detected by the U.V -light-test.
6.2.3 Wipe Test
This test is useful when white light inspection and/or UV light inspection has been inconclusive or not
possible.
The surface is rubbed lightly with white filter paper or with clean lint-free cotton or linen cloth. This
paper or cloth is examined under white light and/or U.V light to find any contaminating traces. Several
areas of the parts surfaces shall be tested. Since it is not acceptable to leave cloth or paper particles
on the equipment, this method is not suitable for rough surfaces.
For example: A contamination of 1000 mg/m2 Oil uniformly distributed would have a thickness of
approx. 1 µm.
Acceptance criteria:
A light oxide discolouration or dust is in some cases acceptable.
Any stain from the presence of oil or grease is unacceptable.
6.2.4 Solvent Extraction
Solvent extraction is one of the methods giving quantitative figures regarding the amount of soluble
contaminants. The method is used especially for inaccessible surfaces or as verification of a cleaning
process or of other qualitative methods.
For most small components it may be easier and more economical to disassemble for inspection or to
inspect before assembly. It should be taken into account that this method of inspection is limited by
the ability to reach and dissolve the contaminants if present. Local contamination in pockets of
complex equipment may be detected using this method of inspection by getting successive slight but
constant indications of contamination. Considerable experience is necessary to assess the results of
this method.
The method is based on the comparison of used and unused solvent. The level of or freedom from
contamination present during solvent cleaning can be closely followed by taking successive solvent
samples during the entire cleaning process until inspection confirms that the acceptance standard is
reached. Checking the amount of contaminants in a used sample is a good indication of the
cleanliness level reached.

The amount of contaminants in a sample can be determined in three ways.
- weight of residue (laboratory test)
- volume of residue (laboratory test)
- light transmission (laboratory test for qualitative figures)
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This method is accurate in determining low amounts of oil or grease residues with small tolerances.
6.2.4.1 Weight of Residue
A known quantity (MS) of a representative sample of unfiltered used solvent is contained in a small
weighed beaker and is evaporated to dryness being careful not to overheat the residue and the
weight (m2) of the residue established. In the same manner the weight (in, ) of residue from a similar
quantity of clean unused solvent is determined.
The difference in weight between the two residues and the quantity of representative sample used is
related to the total quantity (Mv) of solvent used and can be taken to compute the amount of residual
contaminant removed per square metre (mc) of surface area (A) cleaned.
m
c
=
m2
− m ) mv
/ m
A
( 1
s
m1 = weight of residue (clean solvent)
m2 = weight of residue (used solvent)
ms = weight of representative sample (used solvent)
mv = total weight of solvent used
A = surface area of component cleaned
Mc = weight of contamination present per area cleaned.
6.2.4.2 Volume of Residue
A measured quantity of a sample of the unfiltered used solvent can be placed in an Imhoff cone and
evaporated to dryness. The volume of residue can be measured directly and used to compute the
volume contaminant extracted per square metre of surface area cleaned. Greater sensitivity can be
achieved by successive evaporation of quantities of the same extracted solvent batch in the same
Imhoff cone.
6.2.4.3 Light Transmission
A sample of the unfiltered used solvent is compared a reference sample of unused solvent by
comparing light transmission through the two samples simultaneously. The difference in colour or light
absorption of the solvents is a qualitative indication of the amount of contaminants dissolved. The
quantity of any contaminant in a sample can be estimated by analysis techniques e.g. making use of
V or infrared light.
6.2.5 Water Break Test
Drinking or distilled water is sprayed on a surface as horizontal as possible. If the amounts of oil or
grease are very small an unbroken layer of water stays for some seconds. If higher amounts of oil or
grease are on the surface the water quickly contracts and forms small beads or droplets between
water free areas.
6.2.6 Spectrometric, Chromatographic and other Special Methods
The measuring instruments used for these methods are very different. For their use special operating
instructions are necessary. By some of them low amounts of oil or grease contamination can be
detected and measured. In some cases the tolerances are low.
Another method is the Total Organic Carbon Analysis-TOC". The technique is based on oxidation of
the samples in furnace in flowing oxygen. The COZ-concentration gives an accurate quantitative

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AIGA 012/04
value of the total surface carbon content and also semi quantitative information on the presence of
hydrocarbons (the amount of carbon can be considered as being 0,8 - 0,9 of the total hydrocarbon
weight).
6.3 Detection Limits
The results of measurements depend in a physical and optical way on the contaminating agent e.g.
type of oil or grease. This is the reason for the wide range of the detection limits given in the table
below. The quoted ranges are for information only.
Test method
Informative threshold of detection
mg/m 2
bright white light 500 - 1700
UV light 40 - 1500
wipe test 30 - 600
water break test 30 - 60
TOC, solvent extraction < 10
A combination of test methods results in a lower threshold of detection.
6.4 Acceptance Criteria
This section gives quantitative values for two pressure ranges.
The pressure strongly influences the ability of the contaminant to ignite. Contaminants are foreign
unwanted matter that tan have a negative effect on system operation life or reliability. They are
mainly:
a) oils greases detergents
b) other foreign matter (solid particles, dust layers, liquids) being either
- organic substances e.g. wood, paper, cloth, plastics, rubber, adhesives, fibres, paints or
anticorrosive, solvents or
- inorganic substances for instance metal chips, scale, weld splatter, welding rod remnants,
rust particles, sand, water drops, or any other particles.
Maximum allowable quantifies of foreign matters
Pressure
Range
Bar gauge
Oil, Grease,
Detergents,
coatings mg/m
organic
2
Particles Moisture
< 30 500 1 Single small chips or
fibres can be tolerated 2
No drops of water
visible
>30 200 1 Single very small chips
or fibres can be
tolerated 2
No drops of water
visible
1) The values are given considering a uniform distribution of the contamination at a max temperature
of 70 °C.
The quoted figures should be considered as guidance only. Lower figures could be requested
depending on the specific application (type and state of fluid, temperature, pressure, flow,
velocity, product purity), or effects like migration.
2) Clusters of fibres other particles and dust i.e. relative high local concentrations must not be
visible.

6.4.1 Odour Test
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If requested (e.g. for medical gases)- an odour test shall be performed. The odour can be determined
by one of the following procedures:
- During purging operations by sniffing a moderate flow of purge gas from the equipment being
tested.
- From equipment in service containing gaseous oxygen by sniffing a moderate flow of oxygen from
the equipment being tested.
- From equipment in service containing liquid oxygen by taking out a liquid sample for testing.
Odour in the liquid oxygen sample is checked by evaporating to dryness a quantity of liquid in a
loosely covered beaker with a fresh filter paper in the bottom. The cover is removed at the point of
complete evaporation and the beaker is odour tested several times until, is has warmed to above
the freezing point of condensed water on the outside.
The result of the inspection shall confirm the absence of odour. In either of the above procedures do
not place face directly in front of valve or beaker. Instead cup the band and bring some of the gas
being vented towards the nose.
6.5 Inspection records
Records are made of inspections and acceptances for the cleaned equipment or assembly. The
record will include:
a) Identification of the item covered
b) Cleanliness specifications
c) Cleaning method employed
d) Method of inspection
e) Results of inspection
f) Inspector's signature and date
7 Labelling for oxygen service
All equipment components and spare parts delivered single or bulk packed in accordance with this
specification shall bear a label stating that the items have been
- CLEANED FOR OXYGEN SERVICE
Additional information may be included as follows:
- To be kept free from oil and grease particles and water.
- Showing date of inspection and stamps of supplier or workshop.
- Stating the designation of the equipment and its serial number (if applicable).
- Warning of asphyxiation hazard if applicable indicating medium and pressure.
The label must be visible and securely attached to -h item by an appropriate means and not invalidate
oxygen clean condition. Avoid the use of adhesive labels directly on metals as the adhesive may
cause corrosion and/or contamination.
Any other information or notices required relative to shipping storage and cleanliness conservation to
be included on labels is given in Section 6.
8 Conservation of cleanliness
The purpose of this section is to provide protection to conserve the cleanliness of equipment for
oxygen vice during shipping and storage until installation prior to commissioning.

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Once a piece of equipment has been cleaned for oxygen service and certified as conforming to the
cleanliness specifications (see Section 4) it shall be ably protected to prevent contamination.
The protection provided will depend on a number of :ors such as the size and type of equipment,
method of shipping, duration, and conditions of storage.
The packaging material used shall be clean, strong, to be sealed, waterproofed and suitable for the
purpose.
8.1 Protection Methods
8.1.1 Small Equipment
Accessories or parts such as valves, gaskets, etc. shall be packaged individually, after cleaning in a
clean polyethylene tube or, bag and sealed. Any openings on the parts shall be closed with
degreased plastic or metal plugs. The interior of the sealed bag may be evacuated of atmospheric air
or filled with oil free nitrogen.
8.1.2 Large Equipment
Openings on equipment shall preferably be sealed with degreased caps, plugs, or suitable blind
flanges. The equipment may be purged of atmospheric air and filled with oil-free dry clean air or inert
gas at a slightly positive pressure. A notice shall be attached stating that the equipment is under
pressure and the pressurising medium used.
8.2 Pressure Testing
When any test is carried out on equipment after completion of the cleaning operation it is essential to
conserve the oxygen clean conditions. The test medium shall be compatible with the equipment
materials and free from contaminants.
When a hydraulic test is carried out, oil free, clean water shall be used and after testing the equipment
shall be dried, purged, and blown out. For pneumatic testing, oil- free, dry, clean air or nitrogen shall
be used. The testing medium shall be removed before the equipment is put into service.
8.3 Notes
The packing must be carried out in the area(s) temporarily or permanently allocated to equipment for
oxygen service.
All equipment shall be labelled according to Section 5.
The internals of equipment that are liable to rust, that cannot be purged with a dry inert gas, shall be
protected by the insertion of fibre, perforated or porous sachets containing silica gel, activated
alumina or similar moisture absorbing agent. The sachets shall be secured inside the equipment,
preferably to a removable part such as a cap or blank flange.
The equipment shall have a notice indicating that it contains moisture adsorbents, the number of
sachets and their locations.
The adsorbents may contain a colour-indicator that will change colour if saturated with moisture.
Sachets shall, if possible, be connected in groups so that they can be removed together. Small loose
sachets of desiccant shall not be used as they may inadvertently be left inside the equipment after
installation. When removing the sachets, care shall be taken to ensure that they are intact and that all
sachets are removed.

30
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Cleaned components shall be stored until installation in a suitable dedicated area free from
contamination.
The packing shall not be opened until the equipment is ready to be installed. Prior to installation, the
cleanliness shall be checked again to ensure that the specified standard has been maintained, and
that the equipment is suitable for oxygen service.
9 Design and manufacturing considerations for cleanliness
The ability to clean, and the method(s) to be used shall be considered in the design and manufacture
of equipment and components for oxygen service.
Where possible, components shall not have recesses that cannot be directly inspected for
cleanliness.
Preferably, components shall be cleaned prior to assembly, and cleanliness maintained throughout
assembly and testing.
Where this is not possible, trial assemblies shall be dismantled after cleaning and components
examined for cleanliness.
Only approved lubricants shall be used in the assembly of components.
The root weld run on piping systems and small pressure vessels should utilise welding process 141
[Tungsten inert gas arc welding (TIG welding)] to IS0857/IS04063, in order to ensure a smooth root
weld profile on the surface exposed to oxygen.
9.1 Quality Assurance for Cleanliness when Buying Equipment or Components
Any supplier or sub-contractor supplying or cleaning equipment or components for oxygen service
shall be evaluated.
Quality records of acceptable suppliers and sub-contractors shall be maintained.
Evaluation and records shall include, where appropriate:
- Cleaning methods, equipment and fluids.
- Method(s) used to evaluate cleanliness.
- Training and experience of operatives.
- Methods used to ensure cleanliness during testing.
Records of inspections for cleanliness witnessed or subsequently carried out by the purchaser.
Methods used to maintain cleanliness up to and during storage.

Appendix A: Effect of CFC and VOC on the environment
1. Effect of CFC on the Environment / Reasons for their Banning
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CFC due to their high vapour pressure vaporises very quickly and goes directly into the atmosphere.
Since 1974 scientists have established that CFC deplete the ozone layer in the stratosphere.
Only the discovery of the "ozone hole" over the Antarctic in the mid 1980's and subsequent research
brought this problem to the attention of the public and politicians.
Today, it is accepted that ozone depletion represents t global environmental problem.
The ozone layer protects the biosphere against the strong U.V.-radiation of the sun. A reduction of the
layer damages human beings, animals and plants skin cancer and genetic damage). Chlorine,
produced as a result of CFC decomposition is mainly responsible for ozone depletion.
The atoms of chlorine set free one of the three atoms of oxygen from the ozone molecule, which
recombine n an oxygen molecule. Every chlorine atom reacts many times before entering into a stable
combination.
Another negative effect of CFC is the warming up of he atmosphere. Two figures: The "ozone
depletion potential" (ODP) and the "halocarbon global warming potential" (HGWP) give an indication
of he magnitude of the negative effects of different hydrocarbons.
The ODP is defined as the ratio relative to the calculated depletion for CFC 11 taken as a reference.
In a parallel manner HGWP is a relative figure taking the warming effect of CFC 11 as a reference.
1GWP depends also on the atmospheric lifetime.
2. Effects of VOC
An organic compound means any compound containing at least carbon and hydrogen or in which
hydrogen is replaced or completed by halogens, oxygen, sulphur or nitrogen.
A VOC is an organic compound that is volatile under the particular conditions of use and which is
used atone or in combination with other agents.
Main representatives of the VOC in correction with cleaning processes are tetrachloroethylene,
tetrachloromethane, trichloroethylene, and 1,1,1-trichloroethane.
VOC evaporate and, as a result of photochemical reactions, cause atmosphere oxygen to be
converted into tropospheric ozone under certain climatic conditions.
For VOC a factor POCP (Photochemical Ozone Creating Potential) relative to that of ethylene is
defined.
Some VOC as 1, 1, 1- trichloroethane are also ozone depleting.
Some values for the ODP, HGWP and POCP are listed on page 30.
ODP values are taken from the EC-Directive, HGWP and the lifetimes from literature.
Substance Formula ODP HGWP POCP Lifetime years
CFC11
CFC 113
CCl3F
CCl2-CClF2
1.0
0.8
1.04
1.4
60
90
HCFC 141B CH3-CCl2F 0.11 0.1 7.8
HFC 134a CH2F-CF3 0 0.025-0.291 15.5
1,1,1-trichloroethane CH3-CCI3 0.1 0.022-0.026 6.3
Trichloroethylene C2HCl3 0 0 7
Tetrachloroethylene C2Cl4 0 0 0.5
Dichloromethane CH2Cl2 0 0 0.9

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Appendix B: Cleaning equipment working with aqueous agents and solvents
Table of Contents
1 Considerations in the Equipment Selection Process
2 Health, Safety and Environmental Aspects
3 Cleaning Equipment for Aqueous Agents
Working Principles and Applications.
3.1 Mobile High Pressure Cleaning Equipment
3.2 Wash Cabins for Manual Cleaning
3.3 Manual Immersion Cleaning Equipment
3.4 Automatic Immersion Cleaning Machines with Agitation
3.5 Immersion Cleaning Equipment with Ultrasonic Energy
3.6 Cabinet Jet/Spray Cleaning Machines
4 Cleaning Equipment for Organic Cleaners
Working Principles and Applications
4.1 Vapour Degreasing Machines with Chlorinated Organic Solvents
4.2 Immersion Cleaning Machines with Non-Chlorinated Organic Solvents
4.3 Immersion Cleaning Machines with Emulsion Cleaners
4.4 Wash Cabins for Manual Cleaning with Low Volatile Solvents
5 Auxiliary Equipment
5.1 Particle Removal
5.2 Oil Separation
5.3 Vapour Emission Control
6 Figure Index
1 Considerations in the Equipment Selection Process
The selection of the cleaning process and equipment is based on:
- cleaning agent to be used
- surface properties of the parts to be cleaned
- shape and geometry of the material
- the types and amounts of contaminants
The degree of automation, the size and capacity of the equipment is determined from
- size of the material to be cleaned
- required cleaning rate
All equipment must, together with the used chemicals, fulfil as a minimum the legislation for health,
safety and environment.
The choice of equipment has to be based on the efficiency of cleaning versus cost.
The efficiency is controlled by utilising typical samples, written procedures and requested criteria for
cleanliness.
2 Health, Safety and Environmental Aspects
Aqueous cleaning agents may be highly alkaline and corrosive and special care has to be taken to
avoid contact with eyes and skin, which might cause permanent damage. Inhalation is the primary
health concern for cleaning equipment-using solvents, but the degreasing of the skin must also be
considered.
The water jet from a high pressure-cleaning machine can cut like a knife and can also throw loose
particles around. Protective gloves, goggles and clothes must be used.

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The emission to water is the main environmental question for consideration in the use of machines for
aqueous cleaning. The emission to the atmosphere is the main impact from solvents.
The disposal of waste must follow local regulations. The disposal methods used for water-based
processes will depend on type of contaminants, concentrations, pH etc. The residue from a solventbased
process is obtained as a highly concentrated waste, which has to be disposed of according to
regulations in force.
All electrical equipment including that of the venting system must have the correct flame/explosion
proof ratings as defined by national regulations when flammable solvents are used.
For environmental aspects see also IGC document 113/03 ‘ Environmental Impacts of Transportation
of Gases’.
3 Washing Machines for Aqueous Agents
3.1 Mobile High Pressure Cleaning Equipment
Working principle:
Fig. 1. High pressure cleaning equipment
The main parts are a high-pressure water pump and a high-pressure hose with nozzles. The cleaning
agent is applied at low pressure and the rinsing is then performed by high-pressure water with very
high velocity. For more difficult contaminants, hot water is required. In some kind of equipment it is
possible to inject the dissolved cleaner together with the high-pressure water.
Applications:
A high pressure cleaning apparatus is suitable for cleaning of big pieces of equipment with easily
accessible surfaces like outer surfaces of pumps and compressors. Protect water sensitive parts of
the equipment from high-pressure liquid that may penetrate into internal parts.
This kind of equipment can also be used for internal cleaning of pipes. (See Appendix D "Detergent
cleaning of pipes with high pressure cleaning -equipment").

3.2 Wash Cabins for Manual Cleaning
Working principle:
Fig. 2. Wash cabin for manual cleaning
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AIGA 012/04
The equipment can be open or covered by a lid, with or without venting. The pieces to be cleaned are
placed on a grid or a perforated plate. The cleaner can be applied manually by brushing and/or by
spraying at low pressure. The cleaner is then re-circulated via a particle filter. Some types of
apparatus are equipped with automatic spraying with fixed nozzles or a rotating spraying arm. When
the cleaner has become too contaminated for use, the tank is emptied and cleaned.
The cleaning agent is normally used at ambient temperature. Alter rinsing with clean water, drying is
done by dripping off followed by blowing with oil-free, dry, clean air or nitrogen.
Applications:
This type of equipment is suited mainly for intermittent cleaning of small details for instance in
correction with repair and maintenance work.
3.3 Manual Immersion Cleaning Equipment

Fig. 3. Immersion cleaning equipment with means for brushing and spraying.
A) Cleaning vat
B) Liquid level in “immersion mode”
C) Perforated plate
D) Liquid level in “spraying/brushing mode”
E) Air inlet for agitation
F) Cleaner reservoir
G) Filter
H) Pump
I) Spraying/brushing device for manual cleaning
K) Heating element
Working principle:
35
AIGA 012/04
The parts to be cleaned are placed on the perforated plate in the vat. By pumping cleaning liquid from
the cleaner tank, the level in the vat rises so that all parts are immersed in the liquid. The liquid might
be heated and agitated e.g. by air or nitrogen injection.
After a while, the parts should be moved around in the vat for improved accessibility.
When the contaminants have been dissolved, the liquid level is lowered below the perforated plate. If
necessary, remaining contaminants can be removed by brushing and spraying.
The rinsing is normally performed in a separate rinsing bath.
The cleaning efficiency is strongly dependent on the shape and the quantity of the parts to be
cleaned. It can be improved by replacing the air or nitrogen agitation by ultrasonic energy. It should be
noted, however, that these two mechanical energy categories cannot be combined, as the air bubbles
absorb the ultrasonic energy.
The temperature is normally in the range 50-90°C. The appropriate cleaning conditions should be
tested in co-operation with the supplier of the cleaner.
Applications:
Manual immersion cleaning is appropriate for small quantities of small size material. The dimensions
of the cleaning vat set the upper size limit for the material to be cleaned. The lower limit is given by
the mesh size of the basket. Details with dead space, narrow and deep cavities can successfully be
cleaned in this type of equipment.
3.4 Automatic Immersion Cleaning Machines with Agitation
Working principle:
The material to be cleaned is immersed into a bath containing heated cleaning agent. Agitation can
be accomplished by thermal agitation, impellers, liquid nozzles or air injection. The agitation can also
be carried out by rotating, lifting and sinking the material in the bath.
In high capacity plants, the material is continuously transported e.g. in conveyors from the cleaning
bath to one or several rinsing baths. A drying stage may also be integrated in the equipment. For
small and medium capacities, all stages may be integrated in the same machine.
Fig 4 shows a machine in which the agitation is accomplished by up-and-down movements of the
parts in the cleaning liquid.

A) Heating element
B) Lifting beam
C) Up-and-down moving platform
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AIGA 012/04
Fig. 4. Automated cleaning equipment. Agitation by up-and-down movement of the material.
Applications
Automatic immersion cleaning in integrated machines is appropriate for small and medium size
material. Provided efficient agitation can be arranged, details with narrow and deep cavities can
successfully be cleaned in this type of equipment.
3.5 Immersion Cleaning Equipment with Ultrasonic Energy
A) Cleaning stage 1
B) Cleaning stage 2
C) Rinsing
D) Ultrasonic transmitters
The material flow is indicated by arrows in the upper part of the figure.
Fig. 5. Ultrasonic cleaning with different liquids in one bath.
Working principle:
Immersion bath cleaning can be improved by adding ultrasonic energy. The equipment can be
manual as well as automatic.

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An alternating current generates ultrasonic vibrations which give rise to cavitation bubbles in the
liquid. When they implode, mechanical cleaning energy in the form of small jets is created.
Cleaning of small parts can be performed in mesh baskets or in containers with holes, which are
immersed into the main ultrasonic bath. Some of the ultrasonic energy is then lost however.
Containers id baskets should not be made from soft material as they absorb much of the ultrasonic
energy. The cleaning tune in ultrasonic baths is considerably porter compared to ordinary immersion
cleaning.
The liquid in the bath must be free from gas bubbles these absorb the ultrasonic energy. A pump
design should be used which does not give rise to gas bubbles in the liquid. For the same reason, air
agitation cannot be combined with ultrasonic energy. The rinsing and drying might be done in the
same apparatus ( Fig 5 ), but is normally performed in separate stages.
Applications:
Ultrasonic cleaning is generally used for small and medium size parts. The method is not suitable for
porous and soft parts because of their energy absorption properties.
It is important that the ultrasonic waves reach all surfaces to be cleaned. The cleaning efficiency is
strongly dependent on the shape, the quantity and the positioning in the bath of the parts to be
cleaned.
3.6 Cabinet Jet/Spray Cleaning Machines
A) Mist rinsing nozzles
B) Rotating material to be cleaned
C) Heating element
D) Pumps (one for cleaning and one for rinsing)
E) Tubes spraying with nozzles
F) Cleaning chamber
G) Jet flushing nozzles
H) Valve
I) Filter
J) Cleaner/ Rinsing reservoirs (located behind each other)
K) Drainage valve
Working principle:
Fig. 6. Cabinet jet/spray cleaning machine.
This new type of cabinet machine utilises a combination of immersion, flushing and spraying.
Immersion is obtained by increasing the liquid level in the cleaning chamber. During this phase, a
highly turbulent flow is created in the cleaning liquid by jet flushing nozzles. The details to be cleaned
are placed in a basket or drum which can be rotated or rocked in the cleaning liquid simultaneously

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with flushing / spraying from the nozzles. The powerful agitation and mechanical impact gives a very
good cleaning effect, which also may be utilised for decreasing the concentration of chemicals and
the cleaning temperature.
The cleaning stage is followed by rinsing with water from a separate tank in the same unit. It can also
be equipped with facilities for drying, oil separation and chemical dosage.
The whole cleaning sequence as well as the temperature are automatically controlled and can easily
be changed to suit different cleaning situations.
Short over all cleaning times can be obtained. Total time including rinsing and drying is typically 8 - 12
minutes.
Applications:
Small and medium size details can successfully be cleaned in this type of apparatus. Typical
examples are closely packed details with complicated shapes, cavities, crevices etc.
4 Cleaning Equipment for Organic Cleaners
4.1 Vapour Degreasing Equipment with Chlorinated Organic Solvents
A) Cooling zone
B) Vapour zone
C) Liquid solvent
D) Heating element
E) Cooling tubes
F) Vapour evacuation
G) Lifting device
Fig. 7. Traditional vapour degreasing equipment (In some countries only closed installations
are allowed)
Working principle:

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The chlorinated solvent is heated to its boiling point in the bottom of the vat with the vapour rising
upwards. The parts to be cleaned are immersed in the vapour phase in the lower part of the vat (the
vapour zone) where they are suspended during the cleaning process. The solvent condenses on the
surface of the parts, dissolving oil and grease, which drain off together with the solvent, which
accumulates in the bottom of the vat. The surplus of vapour is condensed on the cooled walls in the
upper part of the vat (the cooling zone). Remaining vapour, if any, is evacuated through slots just
below the upper edge of the vat.
This self-distilling principle means that clean solvent condenses on the parts even if the solvent in the
sump is heavily contaminated.
During the cleaning procedure parts with cavities must be turned upside down for emptying of
contaminated solvent.
The cleaning stops when the temperature of -the parts reaches the boiling point of the solvent. If this
happens before the parts are adequately cleaned, the parts have to be cooled down with cold solvent
before the degreasing process can proceed.
Vapour degreasing can be combined with ultra sonic immersion and spraying, usually in separate
areas of the machine.
Regular checks of the solvent in the sump according :o the solvent manufacturers recommendations
is necessary to ensure that the condition of the solvent) being used is always suitable for safe and
efficient use.
Special precautions are necessary including the requirement of entry permits into a confined space,
he use of suitable breathing apparatus and the wearing of protective clothing.
Applications:
Vapour degreasing can be applied to all kind of parts is the vapour can reach and condense on all
surfaces. Problems may occur for small and thin details which ire quickly heated up to the boiling
temperature.
4.2 Immersion Cleaning Machines with Non-Chlorinated Volatile Organic Solvents
A) Venting fan
B) Lid
C) Pump

D) Closed cleaner reservoir
E) Cleaning bath
F) Ultrasonic transmitters
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Fig. 8. Closed immersion equipment for volatile solvents with supplementary ultrasonic.
Working principle
Equipment using volatile organic solvents are totally closed apparatus keeping the operator separated
from contact with the solvent. The parts to be cleaned are immersed into the solvent, which is agitated
by stirring or by ultrasonic energy. Spraying is also used.
The parts are normally loaded into the empty vat, the lid of the cleaning machine closed, and the
solvent pumped in from a separate closed solvent storage tank. After the cleaning cycle is completed,
the solvent is pumped away from the vat. The solvent vapours are evacuated by the venting system
before the lid or door is opened and the details are removed.
Examples of solvent used are alcohol and acetone.
Applications:
This kind of equipment is mainly used for small parts.
Organic solvents have normally low surface tension, which makes them suitable for cleaning of details
with narrow cavities. Generally speaking, when compared with chlorinated solvents and alkaline
aqueous agents, the non-chlorinated organic solvents are less universal with respect to dissolving
different types of contaminants.
4.3 Immersion Cleaning Machines with Emulsion Cleaners
Working principle:
For emulsions, the same type of apparatus can be used as for aqueous cleaners, provided that the
risk with the applied solvent is considered.
When water free solvents with added emulsifiers are used, the cleaning has to be considered as
solvent cleaning. The equipment design and requirements are then the same as for pure solvents.
Applications:
Emulsion cleaners can be used for the same type of parts as for aqueous systems. The penetration
into narrow cavities is better than for pure aqueous systems.
It is important that the water rinsing that follows the cleaning stage removes all high boiling point
residues that may remain on the parts.
4.4 Wash Cabins for Manual Cleaning with Low Volatile Solvents
Working principle
The same type of wash cabins as for aqueous systems can be used with low volatile solvents,
provided they are equipped with venting systems and the solvent properties are considered. Often
these kind of cabins are designed for use with aqueous as well as low volatility solvents.

A) Venting
B) Filter
C) Pump
Applications:
Fig. 9. Wash cabin for manual cleaning.
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This type of equipment is suitable mainly for intermittent cleaning of small parts where all surfaces can
be directly inspected. Examples are cleaning in connection with repair and maintenance work.
Components cleaned by this method must be carefully checked for a residue from the cleaning
solvent.
5 Auxiliary Equipment
Beside the equipment necessary for the cleaning process, there are also different kinds of equipment,
which decrease the amount of waste and may save a lot of money.
5.1 Particle Removal from Process Liquids
The removal of particles from re-circulating process liquids is essential in order to minimise the wear
on mechanical parts like pumps and valves and to avoid clogging the spray nozzles.
The particles can be removed as sediment from the tanks or by different types of filters e.g. wire
screen filters in the piping system.
5.2 Oil Separation
The lifetime and efficiency of cleaners and rinsing water depends on the maintenance of the original
composition of these liquids. By re-circulating purified process liquids, considerable savings can be
obtained in chemicals, water and waste dumping costs.
The oil in the spent cleaner or rinsing water can exist Fig, free oil or as an emulsion.
Free oil can be separated by means of gravity, by filtration or by adsorption. Examples of equipment
used are oil skimmer, lamella separator, coalescence filter, oil adsorbing bag filter, and propylene
filter.

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Emulsified oil can be removed by ultra filtration, chemical decomposition, micro filtration, and
adsorption or biological treatment. Evaporators and vapour compression apparatus are also used.
5.3 Vapour Emission Control
The control of vapour emission from solvent based cleaning equipment is essential from an
environmental as well as safety viewpoint.
In carbon or molecular sieve adsorption equipment, he vapour in the vent air is trapped in adsorption
beds. When the beds are saturated, they are regenerated by steam or hot gas.
Cryogenic condensation can also be applied, atone or in combination with carbon filter. The solvent is
condensed from the vent air in a heat exchanger cooled with liquid nitrogen.
6 Figure Index
The following figure sources have been utilised
Fig. 1 Company catalogue. Alfred K5rcher GmbH & Co.
Fig. 2 J. Skogsmo, C. Norrby, "Handbok i Industriell Rengoring", The Swedish Institute of Production
Engineering Research (IVF), 1994.
Fig. 3 Own sketch.
Fig. 4 Company brochure. Langeds Mekaniska AB.
Fig. 5 J. Skogsmo, C. Norrby,"Handbok i Industriell Rengoring", The Swedish Institute of Production
Engineering Research (I VF), 1994. Company brochure. Viverk Fbrsâljnings AB.
Fig. 7 J. Skogsmo, C. Norrby, "Handbok i Industriell Rengoring", The Swedish Institute of Production
Engineering Research (IVF), 1994.
Fig. 8 J. Skogsmo, C. Norrby, "Handbok i Industtiell Rengoring", The Swedish Institute of Production
Engineering Research (IVF), 1994.
Fig. 9 J. Skogsmo, C. Norrby, 'Handbok i Industriell Rengoring", The Swedish Institute of Production
Engineering Research (IVF), 1994.

1 General
Appendix C: Cleaning of carbon steel pipeline
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This annex deals with the distribution network from the supply stations of oxygen plants to the
distribution stations at customers works.
It does not deal with other parts of a complete network such as piping in the oxygen plant, distribution
piping in the workshop, or at the points of use.
2 Specific Design Requirements
Pipeline shall be designed such that it can if necessary be cleaned by a 'pigging' operation.
Consideration must be given to minimum bend radii and changes involving reductions in pipe
diameter.
Low level points where liquids or debris can accumulate should be avoided.
Where this is not possible low point drains should be provided to facilitate drainage and visual
examination.
Drain points should be permanently blanked after pressure testing and/or cleaning has been
completed.
3 Materials and Components
1 Pipe material - Carbon Steel
2 Pipe fittings - Carbon Steel
3 Proprietary – Pig launcher and catcher.
4 Alternative A
Involving use of components pre-cleaned to oxygen clean standard.
4.1 Initial Cleaning Method
All pipe lengths and pipe fittings to be purchased with internal surfaces blast cleaned. (surface finish
Sa 2 1/2 to ISO 9501-1).
4.2 Initial Inspection
Inspection by direct visual method as per Para. 4.2.1 and 4.2.2 is normally sufficient. Pipe lengths and
pipe fittings to be sealed with caps and waterproof masking tape immediately after cleaning.
Desiccant bags should be placed inside each pipe and fitting as per Para. 6 on pages 27 & 28.
4.3 Fabrication
Exercise care in order to maintain cleanliness throughout subsequent fabrication and testing.
Welds should be inspected as work progresses and any weld repairs executed. Pipe ends must be
sealed at all times except when fabrication is actually taking place. A gas purge should be maintained
during welding and between fabricating operations.
Nitrogen gas may be substituted for argon back purge between welding. Paper dams to limit use of
argon back purge should not be used. Trenches must be adequately drained of water.
Attach pig launcher and catcher to ends of pipeline.

4.4 Post Fabrication Cleaning
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Gauging pig made from oxygen compatible materials should be blown through line using nitrogen gas
or oil free air as the propellant.
Any debris removed from line should be examined to ensure that it is not contaminated by substances
which are incompatible with oxygen.
4.5 Pressure Testing
If permitted by responsible authority, this should be a pneumatic strength test.
Adequate safety precautions should be taken when carrying out this test.
This would normally include having completed 100% radiographic examinations of all circumferential
welds.
If it is not permissible to carry out a pneumatic strength test, clean oil free water to which a
deoxygenating agent and passivation agent has been added, should be used for a hydraulic strength
test.
Repeat pigging operation to remove water.
Open drain points to remove any remaining water.
Purge pipeline with dry nitrogen or clean air (minimum dew point -40°C).
4.6 Post Test and Cleanliness Inspection
Check dew point of purge gas.
Check internals of pipeline for oxygen cleanliness by visual examination of ends and through drain
points.
Re-institute nitrogen purge and maintain until pipeline is ready for commissioning.
5 Remedial Action
Should visual examination show contamination, remedial action should be as per Para. 6.5 of this
annex.
6 Alternative B
Involving use of components that have had components chemically cleaned to remove mill scale etc.
6.1 Initial Cleaning Method
Chemical cleaning by alkaline and/or acid pickling following by rinsing with clean water and
passivation. Additional mechanical cleaning may be required.
6.2 Initial Inspection
Visual inspection to ensure that internals are free from mill scale, heavy rust, paint, varnish and
hydrocarbons etc.
6.3 Fabrication
After fabrication attach pig launcher and catcher to ends of pipeline. Complete post weld examination
as required by Design Code.

6.4 Pressure Testing
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Carry out hydraulic strength test using clean oil free water to which a de-oxygenating agent and
passivation agent has been added.
Pig lire to remove water using a pig made from oxygen compatible material; with nitrogen gas or oil
free air as the propellant.
Open drain points, drain remaining water then close.
Pneumatic test line if required by code.
6.5 Post Test Cleaning
Pass through pipeline two pigs with an approved solvent (such as Methylene Chloride) trapped
between them.
Pigs should be of the abradable type of a material that is both oxygen and solvent compatible.
Pigs to be propelled by nitrogen gas or oil free air.
Examine solvent for presence of contaminants per Para. 4.2.4 on pages 24 and 25.
If contamination is present, repeat test- with fresh solvent until cleanliness is judged to meet the
acceptance criteria in accordance with Para. 4.2:4 and 4.4 on pages 24, 25 and 26.
Remove pig launcher and catcher.
Purge pipeline with dry nitrogen (minimum dew point -40 °C).
6.6 Post Test and Cleanliness Inspection
As Alternative A, Paragraph 4.6.
7 Remedial Action
Should after repeated pigging with fresh solvent, the solvent is still found to be contaminated, possible
remedial action is chemical cleaning in situ using alkaline and/or acid solutions followed by
passivation and flushing with water and then post test cleaning as Alternative B, Paragraph 6.5
above.
Another possible remedial solution is shot blasting in situ using proprietary equipment.
8 Additional Information
Further information on the design, installation, fabrication and testing of a Carbon Steel Pipeline can
be found in the IGC Document 13/02 entitled ' Oxygen Pipeline Systems’.

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Appendix D: Detergent cleaning of pipes with high pressure cleaning
equipment
1 Parts to be Cleaned
Bent and straight pipes.
Welded, brazed and soldered manifolds.
Minimum internal pipe diameter:
� Around 13 mm (Depending on hose and nozzle diameter).
Maximum internal pipe diameter:
� Around 300 mm (Depending on nozzle design and pressure.)
Maximum bending angle:
� 90°
Minimum bending radius
� 100-150 mm (Depending on pipe diameter, hose flexibility etc.)
Material
� Stainless steel pipes/manifolds. Some with brass connections soldered to the pipes.
Maximum pipe length
� Up to 30 m. Depending on hose length, number of pipe bends, pipe diameter.
2 Processing of the Parts before Detergent Cleaning
Stainless steel pipes exposed to different kind of treatment like bending, soldering and welding
followed by pickling and pressure testing with potable water.
3 Cleaning Equipment
A high pressure cleaning equipment with high pressure flexible hose and pipe cleaning nozzles. (See
fig 1).
The backward directed jets from the nozzle pull the hose into and through the pipe while flushing the
internal surface.
Hot potable water or apparatus equipped with water heating facilities may be required for heavy duty
cleaning.
4 Cleaning
The cleaning agent is applied at low pressure and ambient temperature via the hose and the nozzle.
In this sequence, the hose must be transported through the pipe manually.
The cleaner foam must wet the whole internal surface.
The cleaner foam is left 5-10 minutes inside the pipe for dirt dissolving action. During this time period,
the pipe should be rotated/turned around 2-3 times to ensure good cleaner accessibility.
5 Rinsing
The internal surface of the pipe is rinsed by warm high pressure clean water from the pipe cleaning
nozzle. The hose is slowly transported back and forth so that all internal surfaces are in contact with

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the high pressure jet. Rinsing is continued until the pH value of the used rinsing water is the same as
that of the fresh incoming water. (pH value may be tested by litmus reactive paper).
The hose is normally self-transported forward through the pipe, but in case of numerous bends, pipe
restrictions and other obstacles, the hose may need some manual help for transportation.
In some cases, the cleaning/rinsing procedure may be repeated from other pipe openings.
6 Drying
Prior to commencing drying, all free standing water must be emptied from the pipe. Special care must
be taken where dead ends and other pockets exist.
The drying is effected by blowing through hot nitrogen or clean oil free air. It is important to check that
all parts are reached by the hot gas.
7 Cleaning Agent
Water based alkaline detergent. A foaming agent is preferred due to its ability to stick to vertical
surfaces. Several proprietary cleaners are available on the market.
Cleaning conditions like detergent concentration, rinsing water temperature etc. should be determined
through tests and should comply with the detergent supplier's recommendations.
Typical conditions are
� Cleaner concentration 20-50 %
� pH, diluted solution 12
� Rinsing temperature 50 °C
�
8 Safety
Protective clothing, gloves, apron, eye and face protection are recommended to be worn by the
operator whilst carrying out high pressure cleaning.
Skin contact with detergent chemicals should be avoided as serious skin disorder can result.
The manufacturer's product information and material safety data sheets must be carefully studied and
followed.
9 Inspection Method - Direct visual inspection with White Light.
Wipe test all pipe openings. A cloth fastened to a lick may be used for wipe test of deeper internal
surfaces.
10 Conservation of cleanliness
All pipe ends are sealed with plastic plugs.
11 Labelling
Cleaned for oxygen service
Keep free from oil and grease
Inspection date/stamp

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Fig 1. High pressure cleaning equipment and two types of pipe cleaning nozzles.

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Appendix E: Cleaning of a tubular heat exchanger in an ultrasonic bath using
an aqueous cleaning agent
1 Material / Size
Approx. 900 x 4300 mm
Copper/nickel alloy
The outer surface of the pipes and the jacket which are in contact with oxygen have to be cleaned.
2 Cleaning Method
Immersion in ultrasonic bath.
Cleaning agent : 1 % aqueous solution - pH neutral
US-bath: 10 m x 2 m x 1.5 m. 8 oscillators, stainless steel
Duration: 4 - 5 h; during this time period, the exchanger should be. moved/turned several times
with a crane.
Temperature: 50 - 60°C
3 Rinsing
Immersion in a second stainless steel bath with deionised water, 1.5 h at 40 - 50°C. Exchanger
moved/turned 2 times.
4 Drying
In a tent with clean air 4 - 5 h at 30 - 40°C
5 Inspection Method
Wipe test and visual inspection with UV light.
6 Conservation of Cleanliness
Packed in a clean polyethylene bag (thickness > 0.15 mm) and sealed
7 Labelling
The bag is provided in and outside with a label. "Cleaned for oxygen service. Keep free from oil and
grease. Inspection date/stamp".

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Appendix F: Cleaning of parts in an ultrasonic bath using an aqueous cleaning
agent
1. Size of Parts
Generally up to 500 mm, depending on the capacity/dimensions of the bath.
2. Material of Parts
Steel, copper alloys. Cleaning of outer/inner surfaces.
3. Cleaning Method
Immersion in ultrasonic bath with/without pre-cleaning.
3.1 Cleaning Agent
20 % agent in water concentrate pH = 10
3.2 Pre-cleaning
In bath with or without ultrasonic.
Duration : 15 min.
Temperature : approx 60°C.
Solution circulated by pump or slight manual movement of the basket containing the parts.
3.3 Cleaning
In ultrasonic bath (same conditions as in pre-cleaning bath).
If oil spots are visible on the solution surface, this solution has to be renewed as well as the solution in
The pre-cleaning bath. Used solution has to be disposed.
4. Rinsing
Immersion in bath/spraying as an alternative; with at approx. 40 °C.
5. Drying
Purging with dry, oil free air or nitrogen.
6. Inspection Method:
Certificated spot checks by wipe test or water break test.
7. Conservation of cleanliness
Packed in clean plastic bag and sealed.
8. Labelling
With a label “Cleaned for oxygen service. Keep free from oil and grease. Inspection date/stamp”;

Appendix G: Cleaning of a vessel with aqueous agent and solvent
1. Material /Size
Stainless steel or aluminium alloy
Dimensions up to ∅ 3000 x 4000 mm
2. Pre-cleaning
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Prior to welding, vessel shell and ends are pre-cleaned separately with an aqueous agent (phosphate
free with low alkaline content) at a temperature of approximately 50°C, then flushed with
demineralised water for approximately 60 minutes.
3. Inspection before Welding
A wipe test is carried out after the drying operation. If there is any indication of grease or oil, the
pie-cleaning operation is to be repeated.
4. Cleaning
After final welding a tube is installed in order to carry out a complete jet spray cleaning using solvent
141 b (see figure and chapter 3, table 1).
5. Inspection after Cleaning
Quantitative control by solvent extraction (weight of the residue after vaporisation)
6. Conservation of Cleanliness
At all stages of assembly, components are protected against contamination. After inspection the tank
is sealed with degreased flanges and slightly pressurised with nitrogen.
7. Labelling
"CLEANED FOR OXYGEN SERVICE
Pressurised with N2 ………………….bar
Keep free from oil and grease
Inspection date/stamp"

A) Jet tube
B) Injection
C) Condensation
D) Purification
E) Control
F) Disposal
G) Solvent recycling
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1 Material/Size
Appendix H: Cleaning of a vessel with aqueous agent
Stainless steel; volume of the vessel from 1000 to 40000 litres.
2 Cleaning Method
2.1 Mechanical Cleaning
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Before final welding interior surfaces shall be mechanically cleaned (grinding, brushing, grit blasting).
2.2 De-dusting
Internal surfaces shall be swept and vacuumed.
2.3 Degreasing
After welding and hydrostatic testing, a jet spray cleaning operation is carried out using phosphate
free detergent (50°C, duration 1 h) followed by flushing with clean water at 50-60°C.
3 Rinsing
Spraying with de-mineralised water.
4 Drying
Purging with dry, oil free, clean air or nitrogen.
5 Inspection
Direct visual inspection with White Light and Ultraviolet Light.
6 Conservation of Cleanliness
At ail stages of assembly, components are protected against contamination. After inspection the
vessel is sealed with degreased caps and slightly pressurised with nitrogen.
7 Labelling
"CLEANED FOR OXYGEN SERVICE"
Pressurised with N2 …………….. bar
Keep free from oil and grease
Inspection date/stamp"

1. Material / Size
Appendix I: Cleaning of a transportable vacuum insulated vessel
Inner vessel and outer jacket: Stainless steel.
Volume: Up to 500 litres.
2. Initial Cleaning Method
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Shell and vessel ends are purchased pre-cleaned and packed to oxygen standard. Root weld should
be by y TIG welding in order to ensure smooth root weld profile and avoid welding debris.
3. Cleaning Method
Before final welding and isolation of the inner vessel the surfaces are manually cleaned with acetone
using a dry cloth.
4. Pressure Test
Carried out with nitrogen or oil free air. Testing is carried out in a special container or chamber
capable of withstanding a potential explosion of the vessel.
5. Inspection Method
Wipe test and UV light inspection of parts before final welding.
6. Conservation of Cleanliness
At all stages parts are protected against contamination.
Openings are closed with caps.
7. Labelling
"CLEANED FOR OXYGEN SERVICE"
To be kept free from oil and grease
Inspection date/stamp"

Appendix J: Remedial cleaning on a construction site
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Facilities and equipment readily available for re-cleaning on or near a construction site are frequently
limited.
When deciding on the method that can be used to a carry out remedial cleaning, consideration shall
be given to the design, construction, size and materials of construction.
While reference should be made to the original cleaning method, it should be appreciated by all
parties, that duplication of any given cleaning method at another location, is often difficult.
The original equipment manufacturer may be consulted on the proposed re-cleaning method.
Facilities that can usually be provided on site are:
� Portable high pressure steam cleaning
� Pickling baths
� Solvent or detergent baths.
Small localised cleaning can be carried out by wiping with Tint free cloth and a solvent.
Care shall be taken that no hazardous residuals remain.
Care must be taken that the values of oil, grease and other contaminants are below the given figures
acc. to this document.
The cleaning procedure and the test-results should be recorded.